‘Don’t answer it!’ he called to Elise in the bedroom, as he dashed into the hallway. He was too late. Elise was already up, wrapped in a dressing-gown and ahead of him, opening the door. He heard her gasp and saw her jump back as two tall figures stood framed in the doorway. Both were wearing full protective suits with purple neoprene gloves, and their faces were hidden behind double-filtered respirators. Even after all the months of seeing and wearing Covid facemasks in public, even after everything he had just witnessed up in Svalbard, Luke was still shocked to see these apparitions turning up on their doorstep, right here in Battersea. He moved quickly to position himself in front of Elise, obscuring them from her view. But once again he felt a pang of guilt. This was his job, his chosen career in the dark world of espionage, and it had brought this nastiness right into their home. Always, he had tried to shield Elise from anything like this and today he had failed.

‘Mr Carlton?’ He heard a muffled, disembodied voice address him. It seemed to be coming from the taller of the two, but he couldn’t be sure. ‘We’re from the Diagnostics Unit at Porton Down. I’m sorry for the intrusion at this early hour, but we need to screen you. Straight away.’

Luke nodded and asked them to wait outside the door while they got dressed, then followed Elise back into the bedroom. She whirled around to face him, her dressing-gown wrapped even tighter around her shoulders, her knuckles showing white with tension. ‘Luke, what the fuck?’

He put up his hands, about to explain, but she hadn’t finished.

‘No, seriously. What the actual fuck? You disappear for two days to God-knows-where – I don’t ask because I know you can’t tell me – and then you come crashing back into bed at five in the morning, smelling all weird. And now this? You bring two people in spacesuits into our flat and our lives. I’m sorry, Luke, but I really do think I’m owed a bit of an explanation this time.’

He could see that her shoulders were trembling as she said this and he moved to put his arms around her, but she backed away brandishing a warning finger. ‘No!’ she retorted. ‘You don’t get to sweet-talk your way out of this one. Not until you’ve got those horrid people off our doorstep. Now get dressed, finish whatever business it is they want with you and get them out of here. I’m locking myself in the bathroom until they’re gone. Is that clear?’