‘Look, she’s a friend of the Doctor’s,’ pointed out Ryan, opening the passenger door and clambering out into the street. ‘Do you really think that she’d be hanging out with someone dodgy?’

‘She hangs out with you, doesn’t she?’ said Yaz, climbing out after him.

‘Hey!’

‘Come on, you two.’ Graham glared at them. ‘Pack it in. We can argue until the cows come home. Personally I like the girl. The Doc seems to like her too, so that’s good enough for me. Now, shall we get on with looking for these hoodies?’

Graham set off up the stairs to the first floor where Chantelle’s flat was. With a despairing roll of his eyes, Ryan followed him. Yaz stood for a moment. Why was she so wound up about Ace? She tried to tell herself it was just anti-terror training, instinct or natural caution. But it was more, she knew.

The thought kept occurring: Maybe I’m not the first Yaz, but just another Ace: young, adventurous, ready to run and fight through time and space.

But Dorothy McShane was proof that you couldn’t run and fight for ever. ‘Ace’ had left the Doctor and the TARDIS under a cloud of some kind, and whatever had happened between them went deep. Deeper than Yaz would’ve liked.

Oh God, she thought, am I actually jealous?

She dragged herself back to the present, looking up at the flats. She’d been called to plenty of similar developments up in Sheffield in her time. Blocks like these always seemed to attract trouble, and it was always the same – a tiny minority making life miserable for the majority. Her gut feeling was that Graham was probably right, that this was going to turn out to be nothing but bored kids rather than alien abductors, but the only way to prove that was to investigate.

Glad to have something to do, Yaz mounted the concrete stairs. From the first floor she could hear Ryan’s voice. He seemed to be happy about something.

She emerged onto the narrow walkway to see Ryan and Graham talking to a slim, blonde woman from one of the flats.

‘Yaz, it’s Chantelle!’ said Ryan pointing at her excitedly.

‘Yeah, Ryan, I know. It’s who we’ve come to meet, remember?’

‘No, I mean it’s the Chantelle!’ Ryan was grinning from ear to ear. ‘From Checkout Girls vs Sea Monsters and Alien Bikers!’

Yaz sighed. ‘Those particular classics must have passed me by.’

‘Well you must have seen her in EastEnders a few years back?’ Graham seemed almost as star-struck. ‘She was the temporary barmaid in the Vic.’

‘Look, who the hell are you lot?’ said Chantelle grumpily. ‘If this is just about getting signed photos …’

‘The Doctor sent us,’ said Graham.

‘The Doctor?’ Chantelle went very pale. ‘Oh no …’

‘And Ace,’ chipped in Ryan.