Yaz and Ryan shook their heads. ‘Not really.’

  The Doctor looked puzzled. ‘What? Nothing? No sudden nausea? Not even butterflies?’

  A bright yellow butterfly floated along the ground by Ryan and then fluttered innocently away into the distance. Yaz shrugged. ‘I just thought it was that Draconian buffet we had last night.’

  ‘Oh man.’ Ryan pulled a face. ‘Them jellyrat scallops. I was up half the night.’

  ‘There’s something funny going on here,’ the Doctor said, scanning the horizon carefully. Her voice was suddenly serious, as cool as a passing cloud. ‘Give Graham a hand and keep your wits about you.’

  ‘But we’re definitely in Italy?’ Yaz said a little later, when Graham was feeling better and they could continue their stroll down the hillside. The sun was heading for the edge of the world and the shadows were getting longer, but it was still very warm.

  ‘Of course!’ The Doctor sounded as if the matter could never have been in doubt. She strode on with a similar confidence, her boots kicking up clouds of dust. ‘500 BC, give or take. Right on target.’

  ‘And we’re really going to meet Pythagoras?’ Bumping into the great and the good (and sometimes the awful and the bad) from Earth’s history was something of an occupational hazard when travelling in the TARDIS, but Yaz couldn’t imagine she would ever tire of it.

  ‘That’s the plan,’ replied the Doctor, setting off down the hill towards the coast. ‘Crotone is this way. That’s where he’s living around now, with his Pythagorean commune, teaching theoretical maths and stuff.’

  ‘He sounds like a barrel of laughs,’ Graham said.

  ‘Never did like maths,’ Ryan said.

  ‘The square of the hypotenuse is equal to the sum of the squares of the other two sides,’ Yaz recited. ‘That’s his special theorem – I remember it from school. Not sure I’ve ever needed to remember it, though. Until now.’

  ‘Oh, there’s loads more to Pythagoras than maths,’ the Doctor said. ‘He’s a philosopher, traveller, astronomer, mystic, metempsychologist …’

  ‘Metem-what?’ Graham asked.

  ‘He believes in reincarnation, Graham – metempsychosis.’ The Doctor paused to look at them with a twinkle in her eye. ‘And he’s not far off the mark.’

  ‘Heads up,’ said Ryan, pointing further down the hillside. ‘Welcome party.’

  A group of men were struggling up the slope carrying a dead weight. They grunted and cursed with the effort, and then dropped whatever they were carrying on the ground in a cloud of dust.

  ‘There you go!’ one of the men growled. ‘Have a night in the dirt and see you in the morning!’ He aimed a kick at the shape on the ground and then led his fellows off back down the hill towards the village.

  The Doctor, Ryan and Yaz hurried down to where the shape lay groaning. By the time Graham caught up – running in sandals wasn’t easy – they were helping a very old man into a sitting position. His white hair was tangled, his beard was matted with food and he stank of booze.

  ‘He’s a bit worse for wear, ain’t he?’ Graham chuckled.

  ‘Drunk as a newt,’ Yaz confirmed. She’d seen enough of them on a Friday night in Sheffield city centre.

  ‘Wonder who he is?’ said Ryan. ‘Looks like the town wino.’

  ‘Oi – this is my old mate,’ the Doctor protested, concerned. ‘Pythagoras!’

  The Doctor and Yaz helped the old man to his feet, where he swayed for a moment and then fixed Graham with an accusatory, if somewhat bleary, stare. ‘Ghosts!’ he said, loudly and distinctly. ‘The souls of the dead!’

  ‘You sure this is Pythagoras?’ asked Ryan. ‘I mean, great thinker …?’

  ‘They’re lost! And in torment!’ the old man insisted dourly, before ruining the moment with a loud belch. ‘Souls of the dead, y’hear!’

  ‘It’s the booze talking,’ said Yaz. ‘Come on, let’s get him home. Give us a hand, Ryan. He’s heavier than he looks.’

  Ryan slipped one of the man’s arms around his neck and helped take the weight. ‘Where to, bro?’ he asked Pythagoras.

  ‘It’s all right, I know the way,’ declared the Doctor, and headed off down the hill towards the village.

  Back, Graham noted, in the direction the villagers had come from when they dumped the old geezer in the dirt like a sack of rubbish. The setting sun picked out the low terracotta roofs of Crotone in a deep red glow, as if the whole town was ablaze.

  ‘Decent crib,’ Ryan said a little later as they looked around the villa. It wasn’t huge, but it was light and airy and had an excellent view of the Ionian Sea from the terrace. It was a hot Mediterranean evening and Ryan was thankful for his toga and sandals. Somewhere there was a dog barking, but otherwise everything was quiet and peaceful. Ryan wasn’t fooled for a minute, though; the Doctor’s unerring nose for trouble would inevitably put paid to that.

  The Doctor sat on a stone bench with Pythagoras, who was nursing a very sore head.

  ‘Here,’ said the Doctor. ‘Try these. They’re yours anyway. I was returning them.’ She handed him the sunglasses. ‘I’m terrible for borrowing stuff, me.’

  The sunglasses were a fancy leopard-pattern design, and Pythagoras eyed them suspiciously. ‘Are you sure?’

  ‘Just put them on, your eyes look awful.’ The Doctor helped him put the sunglasses on.

  ‘Oh! That’s quite remarkable,’ the old man said, perking up a little as he peered around the room through the Polaroid lenses. ‘My poor head feels better already.’

  ‘Smashing. Now, what have you been drinking for? What’s all this about ghosts?’

  ‘Spirits! The tormented souls—’

  ‘—of the dead, yes, so you said. I didn’t believe it then, and I don’t believe it now, quite frankly.’

  ‘Oh but it is true, Doctor,’ Pythagoras insisted. ‘I swear to you. I have felt the anguish of these spirits. Witnessed their suffering! It is as though something has gripped my own soul and squeezed it hard in a fist of pure ice.’

  ‘The only spirits you’ve seen have been in a bottle, mate,’ said Graham, although his smile was forced. The old man’s description, his soul being squeezed in a fist of ice, was very similar to what Graham had felt on the hillside earlier that afternoon.

  Pythagoras glared at him, although the effect was lost a bit through the sunglasses. ‘I know what I’m talking about.’

  ‘Maybe he does,’ Yaz shrugged. ‘I mean, we’ve seen a fair few weird things, haven’t we? Who’s to say ghosts aren’t real?’

  ‘Me,’ said the Doctor emphatically. ‘At least not the kind of ghosts he means.’

  ‘But these souls – they are in torment!’ Pythagoras insisted.

  ‘Something is,’ the Doctor agreed. ‘And I’d very much like to know what.’

  Outside, the dog was still barking ten to the dozen. Something had spooked it all right. Ryan looked back out into the gathering darkness. He could see lights flickering in the distance, presumably other houses or villas. But beyond that the night was gathering, the stars were out, and the moon was full. Did dogs bark at the moon?

  ‘Can you hear him?’ Pythagoras asked. ‘That dog?’

  They all nodded. ‘Surprised the neighbours don’t complain with that racket going on all night,’ Graham added.

  ‘They do. But the other day I stopped that very dog from being beaten in the street, because I recognised someone I once knew in its voice.’

  The Doctor’s eyes opened wider than ever. ‘Really?’

  ‘Oh yes. My dear, departed friend, Tylos. In the hound’s every yelp and snap, I could hear Tylos’s own words – although I could not understand what he said.’

  ‘Get away!’ Ryan said. He wasn’t buying that for a minute.

  ‘I’m serious,’ Pythagoras snapped. ‘I know I am not mistaken. I can still hear him now. He’s in the courtyard. I had to chain him up.’

  They all listened to the frantic barking of the dog.

  ‘You see, all souls are immortal. When we die, the soul is transferred to another body – a new body. It’s an endless cycle of renewal and rebirth.’

  ‘Metempsychosis,’ Yaz remembered. ‘Was that what you said, Doctor?’

  Pythagoras laughed at this, and then winced, holding his head. ‘The Doctor is living proof of my theory, as no doubt you’ve learned.’

  ‘There’s a little bit more to bodily regeneration than you think, Pythagoras,’ said the Doctor. ‘Not everyone can do it – and I’m pretty sure that dog isn’t the reincarnation of one of your mates.’ Her eyes widened again as a thought struck her. ‘Ooh! Can I have a look at him? The dog, I mean?’

  It was a brindle-furred mongrel of the kind seen all over the world for centuries. Graham identified it immediately: ‘Heinz 57.’

  ‘You what?’ Ryan frowned.

  ‘Fifty-seven different varieties,’ Graham explained. ‘Honestly, don’t you kids know anything any more?’

  ‘I know how to wear a toga.’

  ‘Oi,’ Graham tried to rearrange his robes into a more dignified look.

  The dog was exhausted from all the barking. Its tongue lolled between its jaws and its eyes were wild. Firelight from the wall torches illuminating the courtyard glimmered on its foam-flecked jaws.

  ‘Here,’ Graham said cautiously, ‘it’s not got rabies or something, has it?’

  The Doctor scanned the dog with her sonic screwdriver. ‘No sign of any virus or infection. In fact it’s pretty healthy – apart from the fleas.’

  The dog gave an anguished howl.

  ‘My poor old friend,’ Pythagoras said sadly. ‘Tylos’s very soul is trapped inside a mad dog.’

  ‘Don’t be daft,’ the Doctor said, maintaining eye contact with the animal. ‘There’s some … energy in this doggy all right. But it isn’t human – not even remotely.’

  ‘It’s alien?’ asked Yaz, intrigued.

  ‘Perhaps.’ The Doctor checked the sonic again. ‘This isn’t telling me much.’

  ‘So what’s up with him?’ Graham wondered.

  The mongrel growled and bared its yellow teeth again.

  ‘Careful,’ said Ryan as the Doctor bent closer. ‘It could be faking – if it’s an alien, I mean. Waiting for you to get closer. I saw this film once where—’

  Suddenly everyone in the room seemed to stop, draw a single breath and then look at one another. They had all experienced it – a sudden feeling of sickness, as if everything in the world had just changed, but invisibly. Graham put a hand over his mouth. ‘There it is again,’ he groaned. ‘Here, Doc, I think I’m coming down with somethin’.’

  The Doctor was wide-eyed, holding her hands out as if trying to regain her balance. ‘No, it was just another flux in the local continuum. I felt it too. What about you two?’

  Ryan and Yaz both nodded.

  ‘Horrible,’ Yaz said. ‘I feel dizzy.’

  ‘I’ve had some bad nights out,’ Ryan commented, ‘but I’ve never felt like that.’

  ‘There’s something very not right here,’ the Doctor said.

  ‘Don’t touch that animal!’ shrieked a young woman as she came hurtling into the yard. She flew straight between the Doctor and the dog, pushing her arms out to try and separate them. Her green eyes burned with anger.

  Pythagoras turned to the Doctor. ‘I’m so sorry about this, Doctor. Allow me to introduce my daughter – Myia.’

  ‘Pleased to meet you, Myia,’ said the Doctor.

  ‘Do not touch this … thing,’ said Myia, pointing at the dog. It snarled and then, quite suddenly, flattened its ears and tried to press itself down into the dirt. ‘It is dangerous!’

  In the light of the flickering torches, the dog’s eyes had taken on a strange, golden hue – almost as if they were glowing from within. Graham knew that light could sometimes play tricks with the eyes of animals, making them shine at night, but this was something quite different – not least because, as the dog looked up at Myia, the light seemed to be reflected in her eyes as well.

  Then the dog’s eyes went dark and it let out a tired whimper.

  The Doctor frowned. ‘It’s just frightened,’ she said, steadily and clearly. ‘I don’t think it’s going to attack anyone.’

  The woman glared at her, her eyes still bright in the night. ‘Who are you? What do you want here?’

  ‘This is my good friend, the Doctor,’ explained Pythagoras. ‘You’ve met her before. But she looked somewhat different then, and you were very young, and probably don’t remember. The Doctor and her friends are always honoured guests in my house, Myia, and I would like you to remember that.’

  ‘We just want to help,’ Yaz told her kindly.

  ‘If you want to help, you should leave.’ Myia turned on Pythagoras. ‘You and your obsessions. You have led your followers into dark sorcery – and your family too!’

  ‘Steady on, love,’ suggested Graham kindly. ‘Cup of tea and a little sit down. Do you the world of good.’

  ‘Dark sorcery?’ repeated the Doctor.

  ‘No, Doc, cup of tea,’ said Graham.

  Miya looked at the Doctor. ‘He was initiated into the Ancient Rites by the Egyptian wizard Thoth,’ she declared. ‘He’ll infect us all with his foreign beliefs!’

  ‘That’s all complete nonsense,’ Pythagoras protested.

  ‘Did you or did you not meet with the dark priests of Egypt?’

  ‘I studied under Oenuphis in Egypt – geometry, metempsychosis and philosophy. Not black magic.’

  ‘I have heard you speak with the tongue of a demon! You commune with the beasts of the night!’

  Pythagoras sighed. ‘I studied with the Persian magi in Babylon and learned many new languages. None of them have afforded me communication with evil spirits – until now, and this poor wretched animal. Whatever has possessed you, Myia? This isn’t like you at all.’

  ‘Don’t try to blame all this on me,’ his daughter snarled, and then, with an exasperated cry, she pushed past him and ran from the courtyard. ‘Will no one understand?’

  Pythagoras was clearly distressed. The Doctor shot Yaz a look and she nodded her understanding. ‘I’ll go after her, check she’s all right.’

  ‘Something’s definitely not right here, Pythagoras,’ the Doctor said as Yaz left.

  The old man sat down heavily on a bench. ‘I know. And it’s getting worse.’

  Yaz found Myia in her room on the other side of the villa, sitting on a low stone bench with her arms wrapped tight around her knees. When Myia sensed Yaz in the room, she sat up straight and cleared her throat.

  ‘Hey,’ said Yaz gently.

  Myia sniffed angrily. ‘What do you want?’

  ‘Only to help, if I can.’ Yaz leaned against the doorway. ‘Like, what was all that about? You’ve had more than a bad day, yeah? Anyone can see that.’

  ‘It’s nothing,’ Myia said, tight-lipped. She picked up a handful of pebbles from a nearby flowerpot and started to grind them in her fist like some sort of stress reliever.

  ‘Oh come on,’ Yaz pressed a little harder. She’d had training in how to talk to witnesses and suspects. ‘I know what it’s like when your dad’s driving you crazy with the latest stupid scheme, believe me. What’s up?’

  ‘He’s mad. All that nonsense about reincarnation, about hearing his friend speaking through the hound, saving it from a beating …’ Myia stared into the distance as she spoke. ‘My father drove away the men who had been beating the dog, cursing them for devils and fools. He was very brave. He saved its life, I don’t doubt that. But he only cared for the soul of the man he thought was trapped inside, and not for the animal itself. And he never stopped to wonder why those men were beating it.’

  ‘Do you know?’

  She nodded. ‘Of course. They knew it was possessed by a demon. They were trying to kill it. When they found out he’d saved it they dragged him out of town and left him to rot.’

  The Doctor was kneeling down close to the dog, gently rubbing at the fur behind its ear. ‘What’s up with you, eh?’ she asked softly. The animal was completely docile now, without a trace of its previous bad temper. In the flickering golden light of the yard torches, it looked positively tame. ‘What’s the matter? You can tell me, I’m the Doctor.’

  The Doctor rested her forehead against that of the dog and closed her eyes.

  ‘Don’t tell me you can talk to the animals,’ said Graham in disbelief.

  ‘Wrong Doctor,’ Ryan told him.

  ‘Hush, you two,’ said the Doctor. She sounded very worried, and both Ryan and Graham were instantly on alert.

  ‘This could be it,’ Ryan hissed anxiously. ‘Like in the film, man. When it turns out the alien’s a shape-changer and it just looks like a dog …’

  The Doctor waved him to silence. She looked stricken; her eyes were always expressive, but whereas they were normally full of gleeful wonder at any new experience, they were now dark with concern.

  The dog had closed its eyes and rested its head on the floor next to the Doctor. She continued to stroke the fur on its neck with a gentle hand.

  ‘What’s going on?’ Pythagoras asked quietly, but everyone in the room knew only too well and suddenly the air felt heavy.

  The Doctor gave a sad shake of her head. ‘I’m so sorry, Pythagoras.’ She gave the dog a gentle, final pat.

  Pythagoras gave a small gasp. ‘Is he—’

  She nodded. ‘He’s gone. He’s at peace now.’

  Ryan and Graham glanced at each other. This was too awful. Graham poured a goblet of wine for Pythagoras. ‘Wasn’t there anything you could do, Doc?’

  ‘No,’ the Doctor replied simply, still sitting on her haunches by the body of the dog.

  ‘Poor Tylos,’ said Pythagoras, gratefully gulping the wine. ‘The life that had been inside that stray … the soul … I knew him. I knew him.’

  ‘It may have sounded like someone you knew,’ said the Doctor thoughtfully, ‘but it wasn’t.’

  Ryan frowned. ‘You mean it was something pretending to be someone he knew?’