He halted as close to the two men as he dared without being obvious about it, and stood there on the pretext of reading one of the magazines he was carrying. Ignoring him, the pair continued their conversation. One thing the eavesdropping archaeologist picked up on immediately: The first speaker’s relieved declaration that his bellyache had left him.

  Of all the people wandering in the hall, only Coschocton Westcott knew just how literal was the janitor’s judgment. Refolding the magazine, he resumed his course, having garnered another valuable insight into Interloper behavior. At the same time, the two janitors started toward him. As they did so, their legs became entangled. Mops and buckets went flying, accompanied by startled oaths.

  An alert Cody leaped straight up. The soapy contents of one bucket rushed past beneath his feet, the miniature flash flood carrying with it a pair of yellowed sponges and one sodden pumice stone. As it floated speedily by, the stone put forth a small, engorged, but still hungry Interloper. It missed the front end of the archaeologist’s open-toed Tevas by inches.

  Both men apologized profusely for the near-drenching. While they were doing so, Cody searched their faces, but could find nothing inimical, nothing sly, lurking within. Perhaps the men were innocent, perhaps they were dupes, or maybe it had just been an accident. Another accident.

  Today being Kelli’s day off, he had the car to himself. He was walking toward the parking facility when he saw an Interloper flow from the decorative tree against which a bicycle was leaning into the bike’s owner. Too late to prevent the infestation from taking place, he could only look on with regret as the newly infected, unaware female undergrad began to pedal off.

  That was when he saw the second student, swinging around the far corner of the red brick building on her larger, heavier, mountain bike. They ought to miss each other, he knew. There was plenty of room for them to cleanly pass one another in the paved serviceway between the two buildings, plenty of time for each cyclist to see the other one coming. But having coolly observed what had just taken place, Cody sensed that something less sanguine was about to happen. The infected girl was attractive and lightly dressed for the season, as was her onrushing opposite number. In misplaced deference to the brutal afternoon heat of a desert summer, and for the usual reasons of unjustifiable fashion, neither woman wore protective gear. The sidewalk was searingly hot, rough-surfaced, and unyielding. Raising one hand and waving, he rushed forward.

  “Look out, both of you, look out!”

  Either they didn’t hear him, or chose to ignore a warning neither realized was being directed at them. The girl on the bigger bike was steering with one hand while holding the booklet she was reading in the other. The one who had moments ago become unwitting host to an Interloper had her head down as if lost in unhappy thought, not realizing that the reason for her nonobservance of the route ahead was a consequence of influences beyond her control. Both were moving too fast.

  There was no one else around to second Cody’s warning. Racing toward them while waving wildly, he shouted a second time—too late. An instant before collision the student on the mountain bike looked up to see the other girl bearing down on her, legs churning fluidly, young muscles working at peak efficiency. Dropping the booklet she’d been reading, she attempted to swerve to the right. Her last-minute attempt to avert a collision only worsened the impact.

  Proximity led to realization on the part of the infected woman. As she finally raised her head, her eyes widened and she emitted a soft, startled yelp. Her bike struck the mountain bike broadside, sending both of them crashing to the hot pavement in a lacerating tangle of spokes, handlebars, seats, wheels, and bruised flesh. Cody was at the spot in seconds, reaching down into the moaning confusion as he worked to extricate both injured women from the jigsaw of twisted aluminum and unyielding composite materials.

  The contaminated girl was crying. Her blouse and shorts were torn and streaks of blood showed through. Since she appeared to be in worse shape, he knelt to assist her first. From previous experience he knew that Interlopers could not flow from person to person: Infection could arise only from contact with their natural habitat. So he was not worried as he put one hand on her shoulder and offered reassurance.

  “It’s okay. I’m going to get you out of here.” He eyed her left leg hesitantly. It lay at an awkward angle, bent beneath her. “Do you think you can stand up?”

  “I—Owww!” Looking down at herself, she wiped roughly at her eyes, trying to clear the tears that were obstructing her vision. “I think my leg is broken.”

  “Okay, okay,” he admonished her softly. “Just stay like that. Don’t move.” Raising his gaze, he searched the far end of the passageway between the two buildings. Where was everybody? “I’m going to go call the Health Department. They’ll have someone out here right away.”

  “Not right away. They’re always slow.” Sniffling, the girl suddenly looked up at him—and grinned savagely. “Besides, what’s your hurry?”

  “That’s right. No need to rush off.”

  It was the other girl who spoke. Since she was less seriously injured, he had momentarily forgotten her. He remembered her now, as she threw herself against his back. At the same time, the young woman beneath him reached up with both arms and pulled him downward. As she shifted, he thought he could hear the osseous components of the compound fracture in her left leg grinding against one another. He could see the pain race across her face, but otherwise she ignored it.

  Interloper influence, he surmised. But the girl on his back . . .

  Fighting to throw her off, but not too roughly lest the action exacerbate her injuries, he wrenched around in the grasp of the girl on the ground. Only a great deal of self-control allowed him to kill the scream that threatened to explode in his throat.

  Where the young woman’s eyes should have been were a pair of battered bluish stalks that terminated in sickly yellow eyeballs. They dipped and bobbed, weaving back and forth as they hovered less than a foot from his face. Turning away reflexively, he saw that the beautiful, innocent eyes of the girl on the ground had been replaced by a writhing mass of worms, each boasting a single bulging, oversized eye of their own. Not one, but both of the cyclists were hosts to Interlopers. So intent had he been on observing the newly infected girl that he had neglected to look hard at the other.

  He had been set up.

  But for what? Without a natural habitat to serve as vector, neither Interloper could transfer from one of the female hosts into him. The snarl of bikes and bodies lay sprawled on a pathway of neutral concrete that lapped up against a pair of inert brick structures. The nearest rocks and growing things that could possibly serve as hosts to additional communicable monstrosities lay some distance away.

  “You were told to stop your research.” The girl on his back clung to him with a feral tenacity that belied her appearance.

  “You haven’t,” added the smaller figure beneath him.

  He struggled in their binary hold, wanting to free himself from their grasp but not willing to hurt either of them in the process. After all, neither student was directly responsible for her actions. They were afflicted, suffering from the overriding influence of the malevolent parasites within. Though bigger and stronger, he was having trouble breaking free. Both young women were exerting themselves beyond what could normally be expected of their unremarkable physiques, their bodies driven to their natural limits by those who were presently inhabiting them. The girl beneath him should have been screaming in pain as the broken bones in her left leg grated and ground against one another. Instead, she continued to smile wolfishly at him from beneath the writhing worms that had replaced her eyes.

  “I’m an archaeologist,” he protested. “My research is my life.”

  “None among us could have put it better.” Leaning forward, the corrupted young woman clinging to his back whispered into his ear. “Find other subject matter. Begin a different line of study. And stop interfering with—the feeding.” In a tone so inhumanly chilling he found it difficult to believe it came from so innocent and smooth a throat, the young woman added, “This is your last warning.”

  “You see how easily you can be deceived, despite your irksome ability to See,” declared the figure beneath him. “Ignore this warning at your peril, and sooner or later you will make a mistake. Touch a stone, lean up against a tree, caress the flower that you’re smelling. Eventually you will touch, or lean against, or caress a habitat of occupation, and then you will become one of us.” The glaring worm-face rippled like pustulent grass. “Continue to defy the wishes of Those Who Abide, and your eventual, inevitable hosting will not be pleasant.”

  “From everything I’ve been able to see and learn, none of them are.” With one arm, he swept the girl off his back. She clung ferociously to his left arm, like a leech waving in the wind, reluctant to let him go.

  The empyemic worm-things vanished, sinking back into the smooth-skinned face of the injured girl beneath him. The savage smile remained.

  “It is not necessary to attend you directly, Coschocton Westcott. You may think yourself secure so long as you remain unvisited, but such is not necessarily the case. Your deviant society affords innumerable opportunities for contrivance.” Glancing down at herself, she used her eyes to draw his attention to the tattered state of her clothing. “For example . . .”

  Sudden, artfully constructed fear transformed her expression. Her lips parted wide and she yelled, modestly and not too loudly, “Rape!”

  A stunned Cody started to put a hand over her mouth, stopping when he realized how the gesture might be interpreted by someone newly arrived on the scene. Her perverted grin taunted him.

  “I could yell louder. Much louder.”

  “So could I,” declared the other young woman, whom he had finally shrugged off. Rising, she straightened her clothing. As she did so, the girl lying bent and broken beneath the archaeologist finally released him from her grasp. He stumbled away from her as hastily as if she had suddenly turned into a cobra.

  The girl who had leapt on his back helped her companion to get up. How the one who had lain beneath him was able to stand on her fractured leg Cody could not imagine. The pain ought to overcome even the strongest individual.

  Noting the direction of his stare, the other girl elucidated. “Yes, she is in pain. Severe pain. A good thing, such pain. What is desired is to bring about suffering but not unconsciousness, anguish but not death. A deceased host is no source of nourishment.”

  “‘Nourishment’?” Still dazed by the rapid course of events, Cody was not sure he was hearing correctly. “What kind of sick, diseased relationship is this?”

  “The same kind that you will one day enjoy, Coshocton Westcott. Only it will be the worse for you, if you do not cease.”

  With that, the two girls turned. Perhaps they were aware of the two male students who had come upon the scene and were now rushing forward to offer their assistance. Or maybe the demonstration had coincidentally reached its end. Cody stood staring as the two young men took the suddenly weeping, openly bewildered girls in hand. Now that the Interloper parasites had chosen to slip into the mental and physical background, all the pain and distress of the collision that had heretofore been repressed surged to the fore. The girl who had suffered the broken leg collapsed and had to be lifted and carried. As she crumpled at last onto her ruined leg, the archaeologist thought he could hear laughter. Aberrant, pitiless, demonic laughter.

  There was nothing he could do. Both blameless young women were beyond his help. Grinding his teeth, he turned away and resumed his interrupted march toward the parking facility and his car.

  Devious, they were. He saw now that the danger was even greater than he had supposed. They did not have to infect him with one of their own to affect his course of action or his life. Those they had already contaminated could be malevolently steered into performing actions they would never have contemplated on their own.

  For now, he could see them coming. But as the incident involving the two girls demonstrated, his attention could be distracted, his perception compromised, his judgment hurried. Make one mistake, one wrong move at a critical moment, and he could easily find himself in jail, or worse.

  The consequences of the cycling demonstration were not what the Interlopers intended. All his life, whenever he had been threatened or challenged, it had been Cody Westcott’s nature to fight back with redoubled effort. They had just made a fool of him. He vowed it would not happen again, and not because he intended to comply with their demands or bow to their intimidation. It made him more determined than ever to find a way to disseminate the incalculably valuable knowledge he had acquired.

  He would find someone to help him reproduce the results of Harry Keeler’s work. More of the sacred elixir that had been devised by the Chachapoyan shamans would be brewed. Others would drink of it, if only to disabuse him of his crazy notions of a scourge of invisible Interlopers that were plaguing mankind. With every new convert, each new believer, the ability to resist the malicious organisms would grow.

  Could they be killed? Could one who was “abiding” be destroyed without harming its host? Such vital, unanswered questions only reinforced his determination to continue with and even expand upon his research. Harry Keeler had not known what he faced. Cody did. As he slipped behind the wheel of his car his face was set in a grimace of determination. Let them threaten him.

  Each time they demonstrated a new way of impacting on his life, they exposed more of their abilities. There seemed to be only two: the ability to infect him directly, and the capacity to induce others who were already unwilling hosts to alter their normal behavior. They could draw no lightning bolts down from the sky to incinerate him, spawn no toxic gases to blow into his face to poison him, and could not induce the earth to open beneath his feet to swallow him. He was not invulnerable, but neither did he continue to exist only at their mercy. They were insidious and clever, but they were not omnipotent.

  There had to be a way to kill them. They were fearful of more than his ability to perceive them and to interfere with their activities. Otherwise, they would simply have ignored him. What did it matter if another thousand, or ten thousand, or a million human beings became able to detect their presence, if they could do nothing to alter that presence?

  No, they were afraid of something. That was why they were so anxious to stop him now, before he could uncover whatever it was that they feared. Something must pose a greater peril to them than mere recognition. He, Cody Westcott, was going to find out what that was.

  And then he was going to make use of it.

  In the weeks that followed his confrontation with the pair of possessed cyclists, the Abiders tried to make good on their threat. He prepared as best he could. Though she looked at him askance, Kelli agreed not to touch any bare rocks or trees or plants unless he was present. An experiment, he called it, pleading with her until she consented. Shaking her head and smiling dolefully, she avowed that if her husband was going to be laboring under a continuing delusion, at least it was one that seemed comparatively benign.

  They had the advantage of living in a large city. Too many natural objects, too many potential Interloper habitats existed in the countryside. Native peoples like the Chachapoyans would have been hard pressed to find refuge from the Interlopers. Perhaps that was why city dwellers were more immune than their country cousins to legends and fables of inimical spirits. That supposition alone offered material enough for another entire thesis. It would have to wait. He was too busy staying alive.

  In that respect it was possible he was overreacting. With the exception of Harry Keeler, who posed a direct threat to the Abiders, he had yet to see or hear of an Interloper killing a human being. On the contrary, it would make sense for them to work at keeping their human hosts alive. A parasite without a home might starve to death.

  What, exactly, did happen to an abiding Interloper when its human host passed on? Since they could not translocate directly from one person to another, did that mean the Interloper perished simultaneously? Or did they linger on within the corpse in hopes of coming in contact with stone or wood, of using one or the other as a vector to once more infect someone new? There was so little he knew about them, and he doubted even a comprehensive search of the library’s extensive resources would yield very much in the way of hard information on the biology of imaginary creatures.

  Not that he didn’t have the opportunity to learn from observation. It was frightening to see just how many of the horrors were abroad in the world. His fellow humans went about their daily business unaware of the writhing swarm of nebulous monstrosities that shared their existence. Like some very minor-league superhero cursed with a single unassuming power, he intervened on behalf of his unseeing fellow humans whenever he could. His efforts were not always appreciated by those he saved from infestation, who had no idea of the danger they were in at such moments or the closeness of their respective calls.

  The Interlopers knew, however. They screamed silently at him but were unable to forestall his interference. Time and again at work, on the streets, in a mall, outside a supermarket, and once at a football game, he saved one or more heedless innocents from being infected. Sometimes his efforts drew bemused stares, sometimes indifference, and once in a while, outright uncomprehending hostility. Irrespective of the almost-victims’ reactions, he persevered, knowing that he was doing a good thing, realizing that in his own singular, small way he was helping to keep a tiny portion of mankind healthier and saner than it would have been without his intervention.

  Strolling down the street either by himself or in the company of his wife or friends, seeking shelter from the desert sun, he kept a wary but inconspicuous eye on the raging horde of Interlopers that seemed to populate every third rock, every fourth tree, every tenth bush or planter full of flowers. He watched his fellow pedestrians as well, alert for indications that any might be inhabited by rancorous otherworldly things that danced grotesquely in a light that only he could discern.