‘Ace?’ Chantelle raised a perfectly manicured eyebrow. ‘She’s calling herself Ace again, not Dorothy?’

‘Yeah. Well, maybe.’ Yaz frowned. ‘Is that important?’

‘Not really.’ Chantelle shook her head. ‘If she wants to start using her old nickname again that’s her business, but if any of you start calling me Squeak—’

‘Look, we understand that you might have seen something unusual,’ Yaz interrupted, suddenly suspicious that the Doctor might have sent them off on a wild goose chase just to get them out of the way. ‘Is that right, or are we wasting our time here?’

‘I saw something, yeah.’ Chantelle glared at her, obviously unhappy about being cut off. ‘In the alleyway over there.’ She nodded towards the dark pathway running behind the flats.

‘Aliens?’ asked Ryan. ‘You actually saw them?’

‘I saw something—’

‘Not just kids?’ Yaz interrupted again. ‘Hardly unusual for kids to be causing trouble on an estate like this …’

‘No, definitely not kids,’ said Chantelle icily. ‘I’ve never seen anything like this before.’

‘Can you show us?’ asked Graham.

Chantelle stared at the three of them for a moment, then nodded. ‘OK. You’d better come in while I get a coat.’ She stepped back inside her flat, followed eagerly by Ryan.

As Yaz approached the door, Graham stopped her. ‘What’s going on, Yaz?’

‘What do you mean?’

‘I mean you, coming on all Gene Hunt, all of a sudden. Ace and this girl are on our side you know?’

‘I know.’

‘Well, then. It’s not like we didn’t know that the Doctor had a past …’

Graham followed Ryan into Chantelle’s flat. Yaz stepped in too, feeling troubled. Ace’s past was their future. How did you go back to a normal life after everything that travelling with the Doctor exposed you to? Why would anyone ever leave the Doctor? Was it by choice? Was it because they had fallen out? Was it the Doctor’s decision? Was it Ace’s …?

Dorothy McShane, businesswoman and charity worker had at one point been Ace, travelling companion to the Doctor – travelling through space and time, fighting monsters, putting the universe to rights, just like she and Ryan and Graham were doing. And then it had all stopped.

With a pang of guilt, Yaz realised that however odd a feeling it was for her to discover that the Doctor had old friends, it must be so much worse for Ace to realise that she had new ones.

Making a promise to herself to talk to Ace about the explosives in her workshop, rather than just making judgements about them, Yaz followed the others into the flat.