Alfie Watson is stuck in a rut. A steady job, a caring wife, two teenage sons, his life is fine, just a bit … dull. So when he puts a spy camera into their spare room, which they rent out to guests, it seems like the perfect way to spice things up. But, the first time Alfie watches the footage, he gets far more than he bargained for. Because right there, in his own house, he witnesses a young man murdering his girlfriend and then covering up the crime. What on earth should he do? He can’t go to the police, because they’ll arrest him too. But he can’t do nothing. And then Alfie receives a blackmail note, and it’s clear that this is just the start.