Felix Day, author of the Constantine Sphinx mysteries, and Leonard Fuller, author of the Inspector Fez mysteries, are bitter rivals and the best of enemies. Both happen to present when a notorious author of roman à clef is shot by an invisible assailant during a signing at historic Marlborough Bookstore.

Even if they weren’t both suspects, it’s the perfect opportunity to match wits and sleuthing skills.

If only the murderer was equally amused.