‘Castle’ took a week off after dolling out one of those “serious” episodes we get every once in a while. Fortunately, things lightened up considerably when the show returned last week in fine form.

In ‘Lucky Stiff’, Beckett and Castle investigate the murder of a lottery winner with a compulsive spending habit. The body was found in his expensive, gaudily-furnished condo. Castle, being a mystery writer, immediately suspects that the butler did it. However, a bag of cash missing from the victim’s safe points to robbery as the motive.

The butler informs the police that the bag had a dye pack inside set to explode three minutes after leaving the apartment. This leads to the arrest of a man whose face is covered in blue ink. Cue ‘Avatar’ joke. As per the usual formula, this turns out to be a red (or, in this case, blue) herring. Further suspects include a couple of nogoodniks from the victim’s hometown in Florida who’d just gotten out of prison and immediately came to New York to see their old buddy. Beckett arrests them in the middle of recording a hip hop song with the poetic lyrics: “Move that ass / Move that ass / Get on the floor / Move that ass.” They insist that the victim gave them the money to finance their musical career.

Next, we find that the victim’s daughter used to have a drug habit and was being harassed by her pusher, an elusive character who can only be tracked down making appearances at high-end nightclubs. Castle and Beckett go undercover (using Castle’s Ferrari) as a pair of vapid socialites. This allows Beckett to get close enough to the drug dealer to bust him in the middle of the club while wearing a very tight dress and high heels.

When that lead doesn’t pan out either, we circle back around to the butler, until finally discovering that the victim had won his fortune from a lottery ticket stolen from a dead neighbor. The neighbor’s son found out about this, and attempted to extort a big payday. Then things got violent.

There are two side stories in this episode, both of which follow the money theme. In the first, Castle’s mother Martha inherits $1 million from her dead fiancé, Chet – the man she was on the verge of breaking up with when he suddenly passed away. She feels terribly guilty about this, but the family won’t take the money back. When Alexis suggests that she do something with the money to honor Chet’s memory, Martha decides to open her own acting school – an idea that must make some sort of sense in her own head.

Another running gag has Castle asking everyone in the police department what they’d do if they won the lottery. Beckett is the only one without an answer. This bothers Castle, so he continues to harass her about it throughout the episode. In the final scene, he shows up at her apartment claiming that he finally figured it out. She would want to start a foundation in her mother’s name to follow through with her mother’s “Clean up the city” causes. So that’s exactly what Castle does for her with his own money. Awwww…

In other business, Ryan tells Esposito that everyone knows about him and Lanie. The best moment of the episode, however, happens in that final scene when Castle comes to Beckett’s apartment. He interrupts her lounging on her couch, strumming a guitar, and composing a tune to the lyrics of, “Move that ass / Get on the floor.” It’s a blink-and-you’ll-miss-it throwaway gag, but very funny.