At first, I kind of hated Derry and all her bead-wearing, Namaste-ing, ‘life is a journey’ balderdash. But her particular brand of guru-level Inner Peace was magnetic, and soon I found myself practising her smile in the mirror. It hurt my face. I suspected I might pull a muscle in my neck. Even when I decided that Derry must be on crack – because nobody is that happy just because it’s another day – her indefatigable elation crept into my attitude, and I started finding myself attempting to think happy thoughts. I even printed out and laminated some quotes about positivity for the playroom.

‘What are these?’ Gaia asked when I Blu-Tacked them to the whiteboard.

‘“Happiness is when what you think, what you say, and what you do are in harmony”,’ I read aloud.

‘What?’ she spat.

‘Mahatma Gandhi said that,’ I said. ‘Do you know who he is, Gaia?’

Her scowl deepened into unveiled disgust. ‘What’s wrong with you?’ she said, looking me up and down. And then she walked away.

One day, Derry invited me to accompany her on her morning run.

‘Sorry,’ I said, stifling a yawn. ‘I have to be up for the girls.’

‘Don’t they wake at six thirty?’ she said. ‘We can be back well before that. I usually leave at five, but we can leave even earlier …’

It was the tail end of November. Mid-winter in Norway meant that a cataracted sun cast a resentful smattering of oblique light for approximately twenty minutes each day before giving up the ghost and tagging in Blackest Night. Even Tom had started to talk about investing in SAD lamps for Gaia and Coco, who were even grumpier than usual. An unexpected bonus of the pervasive gloom was that Coco had started sleeping through the night, and occasionally she slept in past seven. Relatively speaking, the supernal bliss of eight hours’ sleep should have gifted me the energy levels of a gazelle, but I’d found that the decrease in sunlight exposure felt like lead being pumped directly into my veins. The slightest effort plundered my energy stores. I was clearly designed for the bounteous rays of Apollo, and I began to loathe Tom for choosing Norway as the locale for his summer home instead of, say, California.

‘We don’t even have to run,’ Derry offered. ‘We can … jog …’

‘I’m afraid I’m not much of a jogger …’ I stammered. In the hours before dawn, I reckoned I would barely be able to crawl.

‘Walk, then?’ she said, her voice breaking at the word ‘walk’. She had these big deep-set eyes, Frodo-blue, that seemed capable of removing my willpower. A perfect nose, perfect teeth. Seven tattoos in a line down her spine – chakra symbols, she’d said, to ‘focus her energy centres’. ‘Oh, come on, Sophie! I promise you’ll love it!’