The Dark Lake by Sarah Bailey

Publisher's Synopsis

A beautiful young teacher has been murdered, her body found in the lake, strewn with red roses. Local policewoman Detective Sergeant Gemma Woodstock pushes to be assigned to the case, concealing the fact that she knew the murdered woman in high school years before.

But that's not all Gemma's trying to hide. As the investigation digs deeper into the victim's past, other secrets threaten to come to light, secrets that were supposed to remain buried. The lake holds the key to solving the murder, but it also has the power to drag Gemma down into its dark depths.