Showing Water Like a Stone by Deborah Crombie

When Superintendant Duncan Kincaid takes Gemma, Kit and Toby to visit his family in Cheshire, Gemma is soon entranced with Nantwich town's pretty buildings and the historic winding canal, and young Kit is instantly smitten with his cousin Lally. But their visit is marred when, on Christmas Eve, Duncan's sister discovers a mummified infant's body interred in the wall of an old dairy barn; a tragedy hauntingly echoed by the recent drowning of Peter Llewellyn, a schoolmate of Lally's. Meanwhile, on her narrowboat, former social worker Annie Lebow is living a life of self-imposed isolation, preparing for a lonely Christmas, made more disturbing by an unexpected meeting earlier in the day. As the police make enquiries into the infant’s death, Kincaid discovers that life in the lovely town of his childhood is far from idyllic, and that the dreaming reaches of the Shropshire Union Canal hold dark and deadly secrets . . .