The agency's ditzy receptionist, Agnes Di Pesto, wins a place on a "murder mystery train" hosted by a famous writer of mystery stories.Maddie and David take her to the station and find themselves trapped on the train as well.She decides to sell off the agency, to the dismay of David Addison, the wisecracking investigator who has been running it.
Richie found $100,000 under the hood of his car, but refuses to go to the police as he is sure the money is "dirty".
The money belongs to a drug dealer, who corners the Blue Moon team.
The detectives set out to find their client's missing son, but find out that he is a contract killer.
Unbeknownst to them, their client (Pat Corley) is also a hired killer and they are caught in the middle as the two men meet for a shoot-out. Blue Moon is hired to provide security at a company run by one of Maddie's friends, which has been plagued by information leaks and sabotage.
David and Maddie do some moonlighting of their own for a debt collection agency when Blue Moon is short of money.