The fourth installment of the popular 'Lesson' series—featuring therapist, professor, and reluctant sleuth, David Unger.

David joins therapy client Bennett, a volatile but good-hearted author, at a Mystery Writers conference in Las Vegas, where attendees dress up as famous detectives and participate in an innocent Whodunit game. So far, so sleuthy.

But all is not what it seems—Bennett's girlfriend has disappeared, and David is tasked with finding her. And he's not the only one on her tail.

The conference cosplay takes a less than cozy turn when a series of dramatic deaths wipes out some of the most famous detectives in mystery history, and David must shift his focus from the object of his affections to the subject of murder.

Faced with a pile of bodies, a missing person, and a fake Whodunit, David must invoke all his voodoo-magic-therapy skills to determine fact from fiction, and expose the truth.