"Now that her ne'er-do-well husband has been arrested for murder, Monk's former assistant, Sharona, is ready to reclaim her place in Monk's extremely well-ordered life. But his current assistant, Natalie, is not pleased with this turn of events. While Monk tries to maintain a delicate balance between the two women, he discovers a few snags in the case against Sharona's husband. And with other murders to investigate, Monk realizes he may be up against...

On a trip to France, Monk takes a tour through the historic underground world of the Parisian sewers and encounters a catacomb filled with ancient human remains--and one much more recent skull.