River Whispers - Rachelle J. Christensen

Jack Bentley’s life fractured into jagged shards of pain and loneliness four months ago when his wife’s car plunged into the Snake River. Still reeling from the loss of his wife and infant son, Jack finds his world shaken again when he sees the ghost of his wife, Gina. But the truth she tells him changes everything: their son didn't drown with her. 
Now, Jack must find his son before he slips away forever. Haunted by loss and his wife's plea, Jack finds himself diving into a mystery deeper than the river's swift current. No power on Earth can reunite him with his little boy—and even help from beyond the grave may not be enough to bring Jack's son back.