The disjointed start to this three-part drama of adult relationships and their effects on children gave an immediate clue to the state of those relationships. This real-world metaphor continued throughout; flashes of the horrifying discovery of a child’s body in a suburban garden interspersed with the story of how we had reached this point over the last three months. A story that proved to be an object lesson in how not to handle your kids during the aftermath of one or more messy divorces.

The complex intertwinings of this mixed-up family unit, which undoubtedly are repeated many times over all across the country, took a while to unravel. Three months before the fateful opening scenes Cameron (Kevin Whately) has just finalised his divorce from Anne (Lesley Sharpe) and moved in with his son Jack (Freddie Boath) to live with new partner Sue (Lesley Somerville) and her daughter Emily (Sinead Michael). With me so far? Good. Because we’re not done yet.

Jack, who’s 14, lives with Anne during the week and with his Dad on the weekends. Emily (7) lives with her Mum (and therefore also with step-Dad Cameron) during the week, but spends her weekends with her Dad Paul (Ian Puleston-Davies), a local radio DJ, his new partner whose name I didn’t catch but who was referred to at least once as “pneumatic tits,” and their new baby Sally.

If the set-up is complicated then the way these relationships are all developing, or more to the point failing to develop, in this raw early “bedding-in” stage is even more complex. Anne and Cameron haven’t really resolved their differences. They’re still biting chunks out of each other every time they speak on the phone. She’s drowning her frustration in tequila during nights out with the girls, and wondering whether to start up a new relationship with a bloke at work who keeps hanging around her looking gormless. Cam is livid that he has to pay the mortgage on her house while she continually dumps Jack at his place.

In the middle of all this Jack, despite being called “light of my life” by his Dad, gets the distinct impression he doesn’t really fit in anywhere. His Mum tears strips off him about the state of his room, and his Dad is too busy trying to impress Sue and Emily to really pay him much attention. He seeks solace in soft-porn magazines, vodka, and riding around the streets alone on his bike at 3 in the morning. You might have spotted that there’s not actually that much solace to be had in any of those things.

Emily’s not having a very good time of it either. Her Dad is regularly late to pick her up for visits. When she’s at his place everyone is concentrating on the needs of the new baby, or the work they’ve had to bring home for the weekend. Worse, the house isn’t set up to be entertaining for a 7-year-old. “There’s some colouring there on the table for you, Em,” says her Dad, turning distractedly back to his pile of CDs. Whoop-di-do.

Emily’s efforts to help with baby Sally aren’t welcomed either, especially after she accidentally drops her on her head. She makes the most of it with her school friends, boasting about how well they get on, but it’s an empty boast. And she never does get the kitten her Mum promised her to cushion the psychological blow of having a new step-Dad and step-brother.

To ramp up the pressure even more, Cam and Sue decide it would be best if Jack moved in with them full-time. Suddenly the two kids, who did little more than pass each other in the hallway at the beginning and end of every weekend, are thrust together permanently. When Cam is busy, Jack becomes default baby-sitter. Teased himself by the real baby-sitter when his paltry porn collection becomes common knowledge, he takes it out on Emily, scaring her during a walk home through the park. The anger moves down the juvenile food-chain as Emily, ignored by her Dad under his headphones, takes baby Sally for an unofficial walk in the park and leaves her buggy parked by the river.

So the scene is set for some major falling out in next week’s episode, and we have at least one obvious and one not-so-obvious candidate for the murder of Emily. For it is her, falling off her swing and crashing her head through the patio window, who is found dead at the beginning, and end, of this opening hour. And the perhaps even more disturbing possibility that her killer will be just a random passer-by, but the accusations and suspicions that this tragedy spark off will tear down the already crumbling edifice of these peoples lives.