Matt and Liz may have retired from the police, but that doesn't guarantee a quiet life.

A deserted building. A face in the window. A face that shouldn't be there.

Photography student Toby Unsworth has found the location for the perfect night-time shoot. A cobbled street in the old part of Fenfleet. Later, when he looks at the images on his laptop, he thinks he sees a woman's face in the window of an old, disused building. He asks his housemate Alex to come and take a look . . .

Two days later, Toby and Alex are dead. Carbon monoxide poisoning. An unfortunate accident. But Alex's mother doesn't believe it. She hires Matt and Liz to find out the truth.

Meanwhile, nine-year-old Simon is missing. He was staying with his Aunt Jessie in a cottage on the edge of the marsh. And his older sister Kellie is increasingly worried.

Matt and Liz's investigations reveal that something very big and very dangerous has descended on the small market town of Fenfleet. And if they don't get to the bottom of it, more deaths will follow.