Castle is picked as one of New York's most eligible bachelors. But a blurb in the paper suggests that he may soon be off the market, as he's rumored to be involved with a certain homicide detective. When Castle's phone rings, he says, "Okay, either Beckett's calling because there's a dead body or because she read the article." As it turns out, there's been a murder. How lucky can a guy get?!
A squatter with needle marks in his neck is found dead on a bed in an apartment belonging to the Dyson family. A hit on his prints reveals him to be Douglass Bishop. Bishop's sister, Melanie, and her husband, Stan, ID the body, but have no idea why he would be squatting. Doug was fine the last time they saw him at his travel agency's holiday party. They were able to attend it because it's near Stan's work at the airport.
A digital camera reveals pictures of a man who may be the killer. Other photos show weapons, vials of the drug used to kill Bishop and layouts of other apartments. Esposito notices prescription bottles in a photo belonging to a Michele Langford, who doesn't know Doug or the Dysons. But when she makes a comment about Castle's picture in the paper, Castle realizes that Michele put a vacation hold on her newspaper. The man in the digital photo was a paper delivery boy named Mickey Carlson.
Mickey says he found the weapons and drugs in an apartment belonging to the Maitlan family while he was taking his photos. He knew something was amiss and decided to relocate, but as he was leaving, he crossed paths with Bishop and two other men. Mickey headed to the Dysons', but Bishop and one of the guys showed up looking for the phone Mickey accidentally took with him from the Maitlans'. The unknown man wanted to kill Mickey, but Bishop wouldn't allow it. Mickey says he took off while the two were struggling.
Castle finds the Maitlan place charming, admiring the molding and a converted dumbwaiter. Nothing seems to support Mickey's story, though, until Castle opens the fridge and a dead body falls out. Sure enough, the body matches the description Mickey gave of us of one of the bad guys.
The new corpse is ID-ed as Anton Francis, a repeat felon. Since Mickey has an alibi for the time of Anton's death, Castle thinks the killer must be the same man who fought with Bishop: the mysterious third man. He must be the mastermind; he had Bishop use his job at the travel agency to get the Maitlans a cruise and hired Anton for his criminal expertise. But to what end? What's in the Maitlans' apartment that's worth all that effort?
Castle thinks the key is the dumbwaiter. It would allow our criminals to sneak into whatever is below the Maitlans. But when Castle and Beckett return to the Maitlans' building, they find the first floor occupied by an exotic pet store. The owner, Noel du Preez, says nothing was stolen. Beckett asks what's on the other side of the back wall and du Preez tells her it's a bank. Ah-ha! But apparently something stopped our perpetrators before they could break in. Beckett figures they were betrayed by the third man.
That night, Castle and Beckett have a date... with other people. See, Beckett found out about the blurb in the paper and had Lanie set her up with a hot fireman. Castle, meanwhile, is out with one of New York's most eligible bachelorettes As luck would have it, they all end up at the same restaurant. Castle and Beckett bore their dates with shop talk, until they both realize that the pet store must've been the real target of the robbery.
Beckett and Castle ditch their dates to work the case. Ryan says the only activity on du Preez consists of some exotic snakes he just imported from South Africa. Castle says snakes are often used for diamond smuggling. Beckett tells du Preez that the snakes he just signed for with Customs aren't in his store. He admits to the smuggling but insists he told no one about his last shipment and doesn't recognize photos of Bishop or Francis.
Castle muses that someone must have known when the snakes were being shipped; someone who had picked up shipments in the past at the airport, maybe. This rings a bell with Beckett. Didn't Bishop's brother-in-law say he worked at the airport? As it turns out, Doug's brother-in-law, Stan, was the Customs agent who processed Noel du Preez's snakes. He roped Doug and old high school friend, Anton Francis, into his diamond smuggling scheme. And when things went south, he killed them. Yes, Stan is the third man.
Castle and Beckett solve the case, but realize they bailed on their dates before eating dinner. So when Castle suggests they grab a burger, Beckett thinks it's a good idea. You could even say...it's a date!