Dauwan Pitchitara, a medical student, makes a pact with the god Thanatos to let him return to the Human World to finish a task. However, he was given only three full moons worth of time to do it. With the aid of a spirit - called a Sentinel - who is a total stranger to him, they look for leads that will let him complete his task - solve the sudden death of his boyfriend, Dr. Exeter Helman.