Maddie had a difficult time giving birth. Her son was born almost three months early, and she lost a lot of blood. She and her partner Pete had gone to a private hospital when she woke up that morning feeling off. But once she’d had her emergency C-section, an ambulance had rushed the baby and Pete to an NHS hospital with a neonatal intensive care unit (NICU). It was several days before Maddie was strong enough to see her baby boy, but Pete stayed in the NICU, knowing that the baby had lost some oxygen during the birth and there was no telling how long he may live.

As the days and then weeks go by, their son Theo starts to make progress. He gets stronger, he gets taken off the machines that had been keeping him alive, and then he gets to go home. Pete says good-bye to the nurses he’s spent so many of his days with and heads home with Maddie and their son, looking forward to a good life as a family.

Two years later, Pete is acting as full-time caregiver to Theo while Maddie goes to work. Theo is sometimes a little aggressive with the other kids at nursery school, but he is happy and healthy, and Pete is doing everything he can to temper Theo’s occasional acting out.

And then there is a knock on the door.

Pete opens the door to find two men on his doorstep. They come in and change Pete’s life forever. One of these men is a private investigator and the other introduces himself as Miles and informs Pete that he is actually Theo’s father. They have a DNA test to back up what they’re saying. At first, Pete thinks that Miles is saying that he’d had an affair with Maddie, but they explain that there had been a mix-up at the hospital, and Pete and Maddie had taken home the wrong baby. Somehow, Miles and his wife Lucy, ended up with Pete and Maddie’s son, David.

It’s so unusual that such a mix-up happens that there are no real legal precedents for what to do next. Pete wants to do right by both children, but he doesn’t want to switch them back. He has bonded with Theo. They’re a family. But he wants to meet his biological son too, so he and Maddie go to their house to meet and get the two boys together.

Miles and Lucy clearly have more resources than Pete and Maddie, and that’s good, as David had clearly suffered some brain damage during his birth. Maddie immediately feels a maternal bond with David, the kind of bond she’d always wanted to feel with Theo but never had.

As the two families spend more time together, the situation gets more complicated. Miles is aggressive, not unlike Theo, but his pushing makes Pete and Maddie increasingly uncomfortable. They join together to sue the hospital that switched the babies, and obstacles pop up in the lawsuit that causes more stress. Pete wants to deal with the situation with respect, communication, and consideration. But Miles becomes less cooperative whenever Pete tries to put up a boundary. Finally, Miles snaps, and cooperation is no longer an option. But how far will Pete and Maddie go to try to save their family?

JP Delaney brings us Playing Nice, a family slow burn thriller that looks at the worst possible problem new parents could face: a mix-up at the hospital means that you are raising someone else’s child, and they are raising yours. It’s a study of relationships, of the cracks that can grow into a rift and the decisions that can help fill the fractures and lead you back to solid ground.

I thought the premise for Playing Nice was interesting, but as the characters became more real to me, it became a fascinating look at how people deal with difficult circumstances. Why decides to play dirty and who plays nice? And, maybe most importantly, who wins in that situation?

Playing Nice takes a very rare situation and turns it into a family’s worst nightmare. Watching how that situation play out is always going to be a good time, and this is no exception. A page-turning ride from the beginning to the end, and lots of chilling twists throughout!

Egalleys for Playing Nice were provided by Ballentine Books through NetGalley, with many thanks.