It wasn’t long before he’d discovered that the bogus accounts allowed him to see the whole picture, the background of everything the boys were going through, the environment in which they lived and interacted and were judged, the ocean in which they swam. Things were said on social media that they would never in a million years say in front of him and now he followed lots of others on Instagram, Snapchat and Twitter. As ever, the beauty of it was that he could be on his phone – looking at literally anything, taking pictures – and no one would be any the wiser. They’d think he was just checking his emails or scrolling through Facebook.

So what were the young folks posting on Instagram today? He started with his boys, scrolling through Saturday’s pictures from the cliff edge, Jake standing on the brink with his arms aloft. Always Jake doing the doing, always Ethan daring him. That was an interesting dynamic in itself. He came out of Jake’s profile and went back to his own feed, made up of their schoolmates and friends. There were copious sun-drenched holiday pictures from various spots on the globe, lots of posts about a girl called Lexie, who was having a sixteenth birthday party at the weekend, a shaky video of some boys dancing in a club, posts about someone called B-Boy with sad face emojis and kisses, quizzes, the usual dogs, cats, food and drink pictures, funny memes, diets, and other random teenage things that Alistair didn’t pretend to understand.

After a few more minutes of light stalking, satisfied there was not too much going on with his boys that he didn’t know about, he typed LucyLupin22 into the search box and selected the account. A selfie of Lucy on the balcony of the villa filled the screen, the landscape spread out behind her. Various other pictures of the beach, the vineyard, the gorge from this morning. He scrolled back further. A picture of Lucy and two other girls, all in animal onesies: a sheep, a giraffe and a panda. It looked like they’d been at a sleepover a few days ago.

OK. That all looked OK.

He switched to his real account and pulled up the pictures he’d just taken a few minutes before: a beautiful sleek creature with perfect features and effortless poise – it made him smile just looking at it. He picked the best one and posted it to his Instagram account with the caption Extra guest at the villa #Cats_of_Instagram.