The Doctor held out a hand to her, and led her back out of the changing room. Sid followed. ‘You two stay here,’ he said, his voice much softer now. ‘I’ll be out in a minute.’

It was more like twenty minutes before the Doctor joined Emma and Sid in the corridor. They weren’t looking at each other. There was clearly no love lost between them. Emma was sitting cross-legged on the floor. She jumped up when the door opened, looking scared.

‘Well?’ said Sid. ‘What happened to them?’

‘They were electrocuted,’ the Doctor said.

Sid looked puzzled.

‘Zap!’ went the Doctor, in case the youth hadn’t understood. ‘A thousand volts, zzzzzz, ow! Water and electricity don’t mix. Don’t take a toaster in the bath, however peckish you’re feeling.’

‘You mean it was something in the swimming pool?’ Emma asked. ‘An accident?’

The Doctor raised an eyebrow. ‘Oh no. No accident. I found burns on the other two because there was no water to spread the current around. There’s something very odd going on here. So, who do you think wants to win so much that they’d commit murder?’

Sid gaped at him. ‘Murder?’

‘Could be.’

The young man shrugged his shoulders. ‘Now you mention it, it wouldn’t really be a big surprise. So, what were you doing roaming around at night, Emma?’

Emma gasped. ‘Me? What about you? Anyway, that doesn’t make sense. All the victims did different sports. If they’d all been swimmers you might be on to something, but they weren’t.’

The Doctor smiled at her. ‘Good point. That means the answer is likely to be something a lot more interesting.’

‘What was that noise?’ Sid asked.

All three went quiet, trying to listen. There was a heavy thumping sound, and it seemed to be getting nearer and nearer.

‘Do you have a marching band that might be getting in some late-night marching practice?’ the Doctor whispered.

Sid shook his head.

They crept down the corridor and peered round the corner. Emma gasped in horror.

Four short, burly figures were trooping towards them. Each wore a dark blue uniform that seemed to be something between spacesuit and armour. There were large, rounded helmets on top. Two carried long, thin devices in their hands. The others held weapons that looked like compact machine guns. The Doctor knew that they were all deadly.

He flung himself back round the corner, pulling Emma and Sid with him. ‘I said the answer was likely to be interesting,’ he said. ‘And that’s what I call interesting.’

‘But what are they?’ asked Sid.

The Doctor took a deep breath. ‘Sontarans!’ he said.

Chapter Three

THE DOCTOR WAITED until the Sontarans had gone past. Then he led Sid and Emma out from their hiding place.

‘We’ve got to get people out of here,’ he told the nervous pair. ‘Sontarans are ruthless and deadly, and no one is safe if they’re around.’

‘But what are they?’ asked Sid, his eyes wide.

The Doctor explained quietly as they crept away. ‘They’re warriors from the planet Sontar,’ he said. ‘They live only for battle, and it’s almost impossible to defeat them in combat. They only have one weakness, a little hole in the back of the neck called a probic vent. If you hit one there, he’ll fall over.’

‘That sounds like good advice,’ said Sid.

‘It’s not,’ the Doctor said. ‘Good advice is to keep as far away from them as possible.’

‘But what are they doing here?’ asked Emma.

The Doctor shrugged. ‘The war must have moved over here. Every few hundred years it heads towards this solar system, and Earth becomes a key battle site.’ He sighed. ‘It’s a war that will never end. The Sontarans have been fighting the Rutans for ever, or that’s what it seems like.’

‘The . . . Rutans?’ said Emma.

‘Big green shape-changing amphibious blobs.’

‘Hold on a second,’ said Sid. ‘Amphibiwhat?’

‘They live both on land and in water. Like frogs. And they’re deadly warriors. Not like frogs. Well, not like most frogs.’ He paused for a second, thoughtful.

‘The common room’s just down here,’ Sid said. ‘Anyone who’s not in bed yet will be in there. I warn you, though, they’ll think this is a plot to rob them of a place in the Games. No one trusts anyone else round here.’

There were two young women and one man in the common room. Sid introduced Karl and Jess, both tall, good-looking and black, just like Sid. Karl was a sprinter and Jess was a long-jumper. The third person was a petite red-headed gymnast called Holly.

All three seemed on edge. The first thing they wanted to know was what had happened when the lights went out. They were expecting bad news – but not the news that the Doctor gave them.

They listened, frowning, while the Doctor explained about the Sontarans. He wasn’t surprised to find they didn’t believe him.

‘It’s a trick,’ Jess said, just as Sid had predicted. ‘You want us to leave BASE so we’ll lose our chance to make the teams.’

‘No,’ said the Doctor calmly, ‘I want you to leave BASE so you’ll gain a chance to live. If you stay here, you are in great danger.’

‘From these Sun-tanners?’ she sneered, clearly not convinced by anything he’d said.

‘Sontarans.’ That was Emma. ‘We saw them, Sid and me. I agree with the Doctor. We have to get out of here.’

‘If I don’t get a good night’s sleep, I won’t be able to run well in the morning,’ Karl said. ‘Is someone paying you to upset my training?’

The Doctor slapped his hand against his forehead. ‘The only running you’ll be doing is running away!’ he told the young man. ‘This is silly! Don’t you trust anyone?’

Sid laughed grimly. ‘You ain’t seen nothing yet, Doctor. Notice that this lot all do different sports? You won’t even get two teammates in the same room. They’d stab each other in the back before you could say “Paula Radcliffe”.’

The Doctor shook his head, amazed. ‘How did you ever manage to work together long enough to cover up three murders? That really was a triumph of selfishness over spite.’

Sid shrugged. He turned to the others. ‘Look, it’s not a trick, right. These monsters have got guns.’

In the end, Karl, Holly and even Jess agreed to go with the Doctor. ‘But if there’s no sign of these alien things, I’m coming straight back,’ said Jess, grumpily.

The six of them made their way upstairs towards the bedrooms. ‘I could set off the fire alarm,’ said Holly. ‘That would wake everyone up, and give them a reason to get out. Then you wouldn’t have to explain all about the monsters.’

‘Nah,’ said Jess. ‘Leave them there. If the monsters get them all, I get a place in the Games.’

The Doctor ignored Jess, but gave Holly a big smile. ‘The fire alarm’s a good idea. But there could be panic, people running here, there and all over the place. Then the Sontarans might get a bit trigger-happy, and we really don’t want that.’

They were still trying to come up with a plan when they reached the upper floor. But it turned out that they didn’t need one. They were too late.

‘Are they the aliens?’ gasped Jess, no longer stroppy. She stared as two Sontarans herded a crowd of sleepy, scared people down the corridor at gun-point.

‘Oh yes,’ said the Doctor. He took a deep breath and pointed away from the Sontarans. ‘Right. You five, that way. Quick and quiet as you can. Use doors, windows, cat flaps, anything, just get out of here and don’t come back.’

‘But what about you?’ asked Emma.

He shrugged. ‘Someone’s got to get the rest of the students out. That’s my job.’ She didn’t look happy, so he kept on. ‘I mean, that’s my job. No pay, no sick days, no desk with my name on it, but it’s what I do. Fight monsters. Rescue people.’

‘I hear you, man,’ said Karl. ‘I’m out of here!’ The tall sprinter hurried off, his trainers making no noise as he ran. Jess, Holly and Sid followed. With a last glance at the Doctor, Emma went too.