The plot? It appears that a serial killer is on the loose in San Francisco, and as the victims pile up, it turns out that they're all in Natalie's neighborhood. There's a mcguffin, too, giving the title a double meaning. While that's going on, Natalie's making an investigation of her own, into the life of a man who's died of natural causes in a seedy hotel. Who was he? Why was he there. Natalie wants to know.
That's enough said. If you like the other Monk books, you'll like this one. If you've never read the other Monk books, what are you waiting for? This is one of the most entertaining series around. Highly recommended.