There's a full moon out which makes for a wild night at the precinct. The team is called to a therapist's office where they find the body of Dr. Ashley Cosway. The doc's face has insults written all over it. Could it be the handiwork of an angry patient? A second homicide call comes in and Beckett sends Ryan and Esposito to check it out. The victim, Frank Anderson, is a retired school teacher seemingly shot during a random mugging. When everyone gets back to the precinct, Castle wagers that he and Beckett can solve their case first. Ryan and Esposito take that action. It's game on! But we're thinking all bets are off if Beckett finds out.
While Ryan and Esposito focus on gang kids who hang in the park where Frank Anderson took his walks, Beckett and Castle look into Hal Ross, a patient who has violent assaults charges on his record. Ross says that he's not their killer, but that Dr. Cosway got into a yelling match with whoever had the appointment before him.
Turns out Evan Hinkle, the guy scheduled for the aforementioned appointment, canceled and Dr. Cosway ended up having lunch with Jason, which means she was yelling at her hubby. As Beckett looks into this, Castle quietly takes bets from everyone else at the precinct. Beckett quickly figures out what's going on. However, once she finds out Jason took out a three million dollar life insurance policy on his wife, Beckett puts down a C-note on her and Castle. Ok, so we misjudged Beckett. Now we're just bummed we can't get in on the action.
[break] Castle and Beckett interrogate Jason, sure he's their man. But when Ryan and Esposito hear Jason say he was at a basketball game, Ryan gets an idea. When Beckett and Castle emerge from interrogation, they see Ryan and Esposito watching last night's hoops game. Don't you just love "On Demand" television? They freeze frame Jason Cosway in the stands at the time of the murder. Think Vegas odds are shifting against Castle and Beckett?
The next day, Ryan and Esposito announce that they have a strong suspect in Eric, the son-in-law of Frank Anderson. Eric's been borrowing money from his father-in-law and Frank's apartment is rent-controlled. Eric ahs a solid alibi though. He was at a friend's birthday bash and couldn't have killed Frank.
Lanie calls everyone down to the morgue, as she believes both murder cases are connected. The same saltwater compound was found on both bodies, which is the equivalent of finding a matching fingerprint. Could the same person have killed both people? The team tracks down a suspect with connections to both victims. They quickly discover that he's on house arrest and couldn't have done it. In the gambling world, we call this a push.
[break] The investigations are back to square one, even though our team is convinced they have the right suspects. They just can't connect them to the crimes. Beckett suggesting swapping case files and Castle gets a thought: maybe their suspects swapped the murders! A quick look at the timeline makes it clear that Eric doesn't have an alibi for Ashley's murder and Jason doesn't have an alibi for Frank's murder. But how are those two connected?
Castle and Beckett discover they both take the water taxi to work! It explains why both bodies have the same saltwater compound on them, since Jason and Eric would both have it on their person from their daily commute. Castle and Beckett bring Jason into one interrogation room, while Ryan and Esposito talk to Eric in the other. Neither is willing to talk, until Castle and Beckett walk in on Ryan and Esposito to announce that they've won the bet, saying Jason cracked and flipped on Eric. Upon hearing this, Eric immediately explains how Jason planned the whole thing.
Afterwards, Castle and Beckett reveal that Jason never confessed; rather, it was all part of strategy to get Eric to confess. It was a gamble, but one that worked. Still, one question remains. Who won the bet? Ryan and Esposito argue that since Eric broke down, they won. But Castle and Beckett say that Eric wouldn't have cracked without their help. We're still not sure who came out on top. The only thing we know for sure is that when there's a murder that needs solving, never bet against anybody on this tea