Now he was surprised. “And you are telling me this?”

  “I am bound to you. I must do your will. I can't betray you. This means I must warn you when you are about to make a mistake. I am doing so.”

  “You hate me so much?”

  “I do not hate you, Neris. I love you. That is the force that binds me. If you free me, I will no longer be bound by that emotion, and will seek satisfaction. It is a matter of honor. A siren can't tolerate being dominated by a mortal man, or even a half mortal man. Mortal males are my natural prey. Vengeance for the insult is required. There are ways you might free me, but I am obliged to acquaint you with the folly that would be.”

  Now he was intrigued. “Is there no way I could free you without risking my life and perhaps my soul?”

  She considered. “There is a way.”

  Was she playing a game here? “Will you tell me what it is?”

  “No.”

  “No? What happened to my will being yours?”

  “Not unless you force me. Neris, I do not believe it is a thing you want to know, and not knowing it will not harm you. I am asking you not to make me answer.”

  “Even though this would facilitate your freedom from the outrage of being bound to a man?”

  “Even though,” she agreed.

  “It's the truth,” Nerine reminded him. “Let her be.”

  And Nerine's advice was always good. “Subject closed,” he said, resigned.

  “Thank you. I will see if I can assist Hedva. I will keep your secret.”

  “Thank you,” he said in return. The dialogue had unsettled him.

  They returned to the normal routine. The nereids brought daily samples of the sea water from their location, which Hedva fed into the machine for analysis and treatment. This was no bucket-sloshing affair; the machine was a multimillion dollar analyzer that provided almost instant readouts of every facet. A single person could now do the job of an army of workers. She knew exactly what was happening as it happened. But that did not automatically provide the solution.

  Siphon went to help Hedva, and as it turned out, there were things she could do. Hedva was weakening, physically, and the siren facilitated things by reading dials and recording results. Siphon did what she could for her, evidently mindful of Neris's preference.

  “Thank you for helping an old woman,” Hedva said wryly.

  “You are ill, not old. I am older than you.”

  Hedva smiled ruefully. “I envy the manner you age.”

  “If you were to accept magical aid--”

  “No.”

  “And I envy your steadfastness, even in the face of extinction.”

  “It's my soul.”

  Siphon nodded. “It surely is.”

  That night Rosie had a suggestion: “You should send the dream to where it counts: the governing body. Congress. They can pass legislation to stop the pollution.”

  “Good idea,” he agreed. “Maybe that will tip the balance.”

  They sent the dream. Again there were no news reports—it was after all a controlled press, only nominally free--but a few days later a bill was introduced to do exactly that. To drastically cut the rate of pollution. The bill was shunted to a committee, where it was as likely to die as to emerge, but it was definitely progress.

  “But not fast enough,” Rosie grumbled. “It will take years for this to mash its way through the system, and meanwhile pollution will continue to harm the world, maybe irreparably. We are close to the tipping point on global health, after which it will be too late to act.”

  “We are proceeding with Plan B,” he reminded her. That was the nullification of existing pollution.

  “Hedva is doing her best. But it's a tedious process, and she's running out of time.”

  “Time?”

  “Her malady is clarifying, her doctors say. She'll be dead in six months.”

  Neris felt a pang. “I thought she was making progress toward our goal.”

  “She is. She has found a way to nullify the specific pollution of the nereids' region. But that's not enough.”

  “Why not?”

  “Nullification requires that the nullifying agent be introduced in the region where there is pollution, and it takes a considerable amount of it to make an impression. The job could take decades. She says that what we need is a catalyst.”

  “Catalyst.”

  “A substance that facilitates a chemical reaction in its presence, without itself being affected, so that it can keep doing the job indefinitely. Introduce a specific catalyst and the process will be self-sustaining, maybe even accelerating, getting it accomplished rapidly no matter how big the sea. Hedva is trying to design that catalyst, but that's more of a challenge. She thinks she's close, but it keeps being not quite right. There's some kind of fine tuning required that is maddeningly elusive.”

  “And she fears she'll be dead before she finds the catalyst?”

  “Exactly. It's frustrating.”

  Neris got an idea. “Hedva won't use magic for herself, but would she allow it in her research?”

  “She might. What's your angle?”

  “The siren has nothing much to do now. She seems to get along well enough with Hedva.”

  “She does. The two are becoming friends in their fashion. They have more than one unifying theme.”

  “Unifying theme?”

  “The Pollution Project, Pollu-Shun. Siphon is a water bird; she doesn't like polluted water any better than she likes polluted air. So she's in harmony with the objective.”

  “That's one theme. What's the other?”

  “They both love you.”

  He laughed. “It's magic inducement for the siren and she knows it. She says she'll kill me if I release her from it. As for Hedva, she knows better.”

  Rosie looked at him. “Maybe. I've researched the phenomenon, and there are older women who fall for teen boys, such as friends of their sons. It can be quite serious. Some have been imprisoned for corrupting technical children. It's not corruption, it's forbidden love. Our society thinks it's okay for an older man to love a teen girl, but is horrified by the notion of the inverse, if that's the proper term.” She smiled briefly. “Or of a woman loving another woman. Society can be the daughter of a dog.”

  Neris was uneasy with this. “We're drifting.”

  “So what's your notion?”

  “Siphon is a magical creature, with an electrifyingly magical voice. Could that voice affect the catalyst?”

  Now she laughed. “I'm no scientist, but I doubt it. But let's ask them. Who knows what might turn up?”

  Next day they did. Both Hedva and Siphon were politely doubtful. “I'm not sure how her voice, however magic it may be, could affect a chemical reaction,” Hedva said.

  It did seem far fetched by the light of day. But they humored him. Siphon held up a vial of grayish sea water and sang a note at it. Nothing happened. She sang another. Still nothing.

  “Try the summoning call,” Neris suggested.

  She sang it. Neris had to fight to stay in place, as the call tugged him forward.

  “Oh, my!” Hedva said.

  The water in the vial had changed color. Now it was reddish.

  “It's probably just an incidental effect,” Rosie said. “Still, it's intriguing.”

  They tested the reddish water in the machine. It remained polluted, but had a different quality. The sound had definitely changed it.

  Now Hedva was intensely interested. “Try it with the catalyst.”

  The catalyst was in this case a vial of cloudy water containing a chemical formula that clarified some polluted water. The problem was that it was the wrong kind of pollution. Hedva had been trying to adapt it to address the right kind of pollution, so far without success. Changing it had simply caused it to become ineffective. It was, she explained, like mutations: ninety nine percent of them were bad, but the one percent that was good made all the difference. She needed to find that one percent. It might be only one percent of one percent, or worse, but she had to look.

  Siphon sang to the catalyst. It changed color. Analysis indicated that it remained catalytic, but now facilitated a slightly different process.

  “That's what we need!” Rosie said enthusiastically. “If we can just get it to address the right pollution!”

  Siphon smiled. “I am glad to help.”

  “And she's not just saying that,” Nerine murmured to Neris. “She wants her friend to succeed.”

  Hedva and Siphon got on it, working even more closely together. If there was progress, it was slow, but it was a promising new lead. Day after day they tried new variants of the song, incrementally zeroing in on the desired solution. Both were fascinated by the prospects.

  “The chemist and the siren,” Rosie remarked, shaking her head. “Who would have thought it? But it's our best lead yet.”

  Then one afternoon the silent castle alarms went off, as they did when anything metallic, like a gun, intruded. Neris hurried to warn Hedva, as it seemed likely that she was the target, as Kelsey had warned long before. “Hedva!” he called as he entered the lab chamber. “Get out of sight!”

  “We have an experiment in progress,” Hedva said. “It can't be interrupted.”

  Then an armed man burst into the chamber. He didn't hesitate. He drew his pistol and aimed at Hedva.

  But Siphon was already in motion, flying across the room like a monstrous bird, which of course she was. She positioned herself between the gunman and Hedva as the gun fired.

  Then Neris was on the gunman, clubbing him in the head with a fist. It was no token blow; Neris was a powerful young man with inhumanly fast reactions, and his closed fist was like a rock. The man dropped as if clubbed, as indeed he had been. Neris quickly tied his hands with stout cord.

  “Siphon!” It was Hedva in anguish, running to her friend. Siphon was a heap of winged flesh, her blood spreading across the floor. Hedva tried to pick her up, but lacked the strength.

  “Medics!” Rosie snapped into the intercom. In moments the staff medics were there, tending to the siren, efficiently stopping her bleeding. They knew about her, as all the castle staff did.

  “Ambulance!” Rosie said, lifting her cellphone.

  Siphon lifted her head. “No! I can't go to a human hospital!”

  “Of course you can't,” Rosie agreed. “Lost my common sense there for a moment.”

  A medic looked up. “The wound is serious. She will die in hours without treatment beyond what we can provide.”

  “What will help you?” Neris asked Siphon. But he got no answer; she had sunk into unconsciousness.

  “Ouroborus,” Hedva said. “The source of the immortality elixir.”

  Neris was surprised that such a suggestion would come from her, but realized that though Hedva would not accept magic treatment for herself, she would for a magical creature. “I'll go there,” he said.

  Neris ran out of the castle as the police sirens were approaching. He knew that the castle personnel would hide Siphon and turn the gunman over for invading and shooting in the building. Also that this time they had a lead to the source of the mischief; the origin of the contract would be traced, by the police and telepathically by Nerine. Even if it came to nothing, it would be a warning to the assassin. Probably the attacks would stop. He jumped into his car and took off.

  Fortunately there was little traffic at this hour. He zoomed through red lights and stop signs and reached the beach in record time. Nerine undressed him with his cooperation as he drove, limb by limb, section by section. Naked, he leaped from the car and ran across the beach. Nerine ran beside him, cloaking him in spot mist so that his state of exposure was not readily apparent. He dived into the water and swam straight out to sea.

  And found himself by the giant serpent's head and chewed-up tail. Ouroborus had seen him coming, as it were. But that did not necessarily mean that his plea would be granted.

  “I beg of you, a drop of blood!” he said, opening his mind to show his reason for the request.

  For a siren?

  “She sacrificed herself to save Hedva! I can't let her die!”

  The Goddess Rhea appeared, regal as ever as she walked along the serpent's back, treating him as a highway. “Oh, come on, Tailface,” she said. “You know it's for a good cause. Siphon's not a bad sort, as sirens go, and she's really helping their effort. They need her song to make the catalyst.”

  Ouroborus didn’t argue. Granted. Evidently the mother of gods was especially persuasive, considering their association.

  “Thank you!” Neris exclaimed. Then he was stopped short by the realization that he had no way to transport the drop of blood. He had never thought to bring a vial.

  “A vial's no good anyway,” Rhea said. “For this purpose it has to be transported in a living body.” She drew him down with her beside the bleeding tail.

  “But I can't take it!” Neris protested. “It's for Siphon.”

  “Posh. In selective storage, of course. Give it here.” She reached for his penis, caught it, and massaged it alert in an instant. She bent down, put her mouth to the serpent's gory tail, and sipped a drop of the blood. Then she put her mouth on Neris's penis and blew, as she had before. Again fluid coursed backwards along the tubing to find refuge in his prostate. Finished, she lifted her head. “That will be diluted in semen, so it won't burn her. You know where it goes.”

  “Uh, yes. Thank you.”

  “Now be off with you,” she said tartly. “Don't keep the poor girl waiting.”

  He didn't dare argue, any more than Ouroborus did. He swam back the way he had come.

  “Grandma's quite a gal,” Nerine said as she paced him.

  He didn't argue with that either.

  They were back at the castle by evening. Siphon was lying on her bed with her head on Hedva's lap. She did not look at all well.

  “I have it,” Neris said. “One drop of Ouroborus' blood.”

  Siphon opened her eyes. “Give it to Hedva,” she whispered faintly.

  “But it's for you,” Neris protested. “To save your life.”

  “Save hers instead. That blood will youthen her to her prime, and extend her life by years, maybe decades, maybe even until there's a cure for her cancer. In any event, enough for her to complete her search.”

  Neris hadn't thought of that. “I don't know.”

  “I do,” Hedva said briskly. “I won't take it, not just because I won't take magic. Siphon put her life in peril to save me, and I will not let her throw it away now that she can be saved. That's final.”

  “I think that's it,” Neris said. “Will you accept it now?”

  The siren pondered for a moment, thought almost visibly coursing through her head. “In that case, yes. No sense in wasting it.”

  “It's in my--”

  “I know where it is.” She spread her thighs. There was a bandage on her belly, colored with blood; it seemed they had been unable to completely staunch it.

  He got on her, and in her, and stretched out above her, careful about the bandage, his face coming almost up against Hedva's bosom because of the position of the siren's head. He kissed Siphon, and she kissed him back, weakly. Her body was cool, limp, only a fraction of its normal vigor. Even her wings looked creased and worn. Now she looked her age, being only a shadow of her usual self; the wound had seriously depleted her. Would the blood elixir restore her this late? It had to!

  He held the kiss and thrust, carefully, and the precious cargo forged out of him and into her. He hoped the embedded drop of blood found its mark, as had the love potion before.

  The effect was immediate. Her body became firm and supple throughout, spreading from her groin, and her cool flesh warmed. Her kiss became intense. Suddenly she was no longer a victim, but all woman.

  He broke the kiss and looked at her. Her color was back and her eyes were flashing. There was no doubt that the blood had been effective. Yet there was something different about her, that he couldn't place. It hardly mattered, as long as she was better.

  “Get away from me,” she murmured urgently.

  “Do it,” Nerine said.

  He pulled out of her, his load delivered. The bandage had fallen off, and the wound in her belly was gone without trace.

  She smiled. “Thank you, Neris. I am whole again. I will remember.”

  “You're welcome. You did a fine thing.”

  “Perhaps.”

  He got back on his feet. Nerine handed him his clothing, which he had never put back on after leaving the sea. He dressed.

  The routine continued, as Hedva and Siphon zeroed in on the catalyst. They were making progress, but the chemist was almost visibly declining. The doctors agreed: she would die in days.

  “We need to talk,” Siphon said.

  Hedva smiled. “As if we haven't been talking daily? Perhaps you do not see it the same way, but I prefer to call you my friend.”

  “I do call you friend,” Siphon said. “That is what this is about.”

  Neris stepped back, about to give them privacy, but the siren stopped him. “You need to hear this too, Neris.”

  He stopped, embarrassed. “As you wish.”

  “Something about the serpent's blood,” Siphon said. “It made me whole again.”

  “Yes, so you said,” Hedva agreed. “I am glad of it.”

  “It cured not only my physical injury, but also my emotional one. It freed me from captivity.”

  “Freed you?”

  “I am no longer bound to Neris.”

  Oh, no! Was she about to attack him? Yet why hadn't she done so when she was first freed? She had continued to work with Hedva, and had had numerous opportunities to tackle Neris.

  Now Neris understood why Siphon had warned him away after the cure. So she wouldn't try to kill him.

  It was Hedva who asked the question. “Why did you remain with us?”

  “Because we had a bond. We both loved Neris. You would not overstep the boundaries defined by your formal status as his teacher, though he loved you. He would not come to me; in fact it was his love of you that boosted his emotional resistance to me and helped him defeat me. So he was yours, not mine.”