Beckett and Castle investigate a murder of a young executive involving antique guns, a 200-year-old bullet, and New York’s steampunk subculture. In this week’s episode Castle and Beckett team up to solve a murder in Central Park. But the clues are confounding. What do a 200-year-old bullet, antique pistols and turn of the century clothing add up to? If you’re Castle the answer is an easy one, a time traveling killer.

In a charming opening we find Castle making breakfast for Alexis and his mother. A new creation he has come up with combining the sweetness of marshmallows, chocolate and…eggs?. Castle says it is a smore-let. Alexis tries it and as expected the experiment is disgusting. She asks her dad if she can invite her friend Ashley over that night. And she runs off. Grandma lets it slip that Alexis is in love. Castle is hurt that she didn’t tell him first. 

Castle meets up with Beckett to look at a crime scene in the park, a gunshot victim in his boxer shorts. Castle apparently wears the same brand and tries to get Beckett to tell him what she wears. Thong, granny panties, anything at all? They discover that the victim is a young mathematician working on Wall Street named Goldstein. 

The bullet that is extracted is a strange clue. It is a lead ball with 200-year-old rust around it. Crazy! This leads Castle to one conclusion. Time traveling killer! Beckett lets him run a bit with his theory and suddenly there are Time Ripples and a possible Time Machine involved. Beckett tries to reel him in. If it is a time traveler why would the bullet be covered in rust? Castle wonders “What if time travel causes rust?” Yeah, Beckett replies, on your brain. The lead ball was fired from an 18th century flintlock pistol. Very cool, except for the killing part of course. 

But why would the killer steal the victim’s clothes. Castle jumps in again. Time traveling killer went through the time ripple and came out naked and needed Goldstein’s clothes? Really, Castle let it go. 

They find out that the victim was involved in an investment scheme that went under causing many investors to lose millions.

They eventually get an ID on a print that was found on the victim’s wallet and bring the guy in. This suspect, however, is a little too big, a little too violent, and throws poor Detective Esposito through a wall. Beckett interviews him and it’s just so much fun to watch how she’s not even flinching at the size of the guy, while Castle screams like a little girl and jumps out of his chair when the guy stands up. That scene is just downright hilarious.

Esposito is furious that he was assaulted by the suspect and Captain Montgomery promises him that with the amount of other charges the guy was already facing, he’ll be locked up for a long time. The fact that Esposito needs a neck brace is a source of endless jokes throughout the episode.

Ryan and Esposito track down the victim’s car and guess what? It’s a Delorian! It comes complete with a flux capacitor and a reactor core! Back to the Future anyone? The next breakthrough comes with the recovery of the victim’s clothing. A homeless guy saunters down the street in an 18th century Victorian suit with a bloody bullet hole in the shirt.

Eventually, they track down a guy who just happened to collect antique guns and was part of the angry mob that had lost millions after Daniel’s mistake. He denies having killed him, but says Daniel once asked him where he could get a Sherlock Holmes gun. 

Gunshot residue is found on the sleeve and glove that are recovered and it becomes apparent that he was fired on and he fired back. When another lead ball is found back at the crime scene Castle’s eyes light up. Antique bullet, costume, two men at midnight in the park at about 40 paces from each other means a good old-fashioned duel! 

That night Castle busts into his front door with a newly acquired antique pistol of his own scaring the daylights out of Alexis and the boy she was totally making out with on the couch. It turns out the boy is Ashley and Alexis’ boyfriend. A fun father meets boyfriend moment happens with a lot of babbling from poor bewildered Ashley while Castle absently waves his pistol around. 

A lead brings them to a club where the door keeper uallows entry based on correct answers to questions pertaining to the works of Jules Verne and H.G. Wells. What greets them beyond it is 1892 Victorian London, a steam punk club! It is a sub culture of science fiction that combines the simplistic elegance and romance of the Victorian era with the ingenuity of futuristic design. We can see Castle is fascinated. 

Are antiques guns so inaccurate? Only one way to find out and in an amusing target practice it is proved that the antique guns are wildly inaccurate shots.

Alexis spills the beans about her thinking she’s in love to Castle and they have a lovely father-daughter moment with Castle in a steam punk get-up. 

Then back at the precinct after they wrap the case in walks the gorgeous Victor Webster! Turns out his name is Josh and Beckett’s boyfriend? Where has she been hiding him? Castle looks crushed! So we will have to see how this pans out and what we will find out about Josh. The triangle appears again.

The episode ended with a tribute to late author Stephen J. Cannell, a guest star throughout Seasons 1 and 2 who passed away on September 30th, 2010.