Besides being Ellen’s best friend of almost a decade, Alexa – bright and considerate, with shoulder-length blonde hair that fell just so – was also the de facto leader of the house. She had three younger siblings, four dogs and three cats, not to mention nearly twenty years’ experience handling two parents who could not be in the same room together. Consequently, she was good in a crisis.

‘Yes, we should.’ Alexa would know what to do. She would also, effortlessly, take charge, relieving Ellen of the burden of doing so. ‘I’m going to go get her.’ Ellen negotiated her way through the obstacle course of boxes again. ‘I’ll be two seconds. While I’m down there, can you have a look for the water box, please? It must be here somewhere,’ she added, uncertainly.

As Ellen hurtled down the stairs, she recalled an occasion when she had watched with fascination as Jack, slowly and methodically, devoured an entire 300ml tub of crème fraîche after dinner. When she asked him why he’d eaten it, he looked nonplussed and said he’d thought it was a yoghurt. Still, perhaps he’d unearth the right box by mistake, Ellen thought, like that theory about a witless monkey with a typewriter eventually writing the complete works of Shakespeare.

Feeling the tingle of adrenaline in her limbs, Ellen rapped loudly and insistently on Alexa’s door. Alexa, like most people who didn’t come home and make themselves a vodka tonic nightcap, probably wouldn’t mind being woken up. Ellen didn’t think she’d gone out last night – and 8.16 a.m. was fairly late for Alexa. This different approach to things like lie-ins (see also: tidying up) was probably why Alexa was a civil servant and Ellen worked in communications for a CBD tampon company.

There was no answer on her first go. Ellen rapped again, even more insistently. She leaned her head forward, listening for sounds of movement. On the third try, she heard the murmur of voices. Plural?! Last night’s white wine quickened her pulse again. She noticed that she was now holding her breath.

‘Lex?’ she said, cautiously.

Another murmur, and a gruff laugh. Ellen heard the bed creak and footsteps padding across the floor. Alexa opened the door and leaned on the door frame, one slim thigh snaked around the other. Ellen reeled slightly at the sight of this grungy Alexa, in checked pyjama shorts and an unfamiliar baggy black T-shirt. In the doorway, she seemed tiny and Ellen, who was about four inches taller, felt like a hulking giantess. Kohl still ringed Alexa’s big blue eyes, and she had a black, chalky stripe down her right cheek. Still, her hair was perfect.

‘Hey,’ Alexa smiled. She looked sleepy and a little sheepish. ‘What’s up? I heard someone scream.’