Girl in the Lake. A Lacey Summers PI Mystery, #4

A young woman comes to in a cold, Minnesota lake and fights her way to shore. Shivering, barefoot and afraid, she can't remember who she is or how she got into the lake. She sees a house and goes there, seeking help and warmth. Don, a handsome doctor and his mother name her Penny and help her recover. With no memory and in fear for her life, she hires Lacey, a PI, to help her figure out who she is and why someone wants her dead.
Will Lacey succeed before Penny's attacker tries again?