On this week’s Castle, entitled “PHDead”, we find ourselves in a kinky situation, and Castle and Beckett get trapped in a prison of the mind.

Let’s recap:

Castle is getting empty nest syndrome and insomnia, as he tries to deal with life after Beckett. The longing looks at her side of the bed are enough to break our hearts.

Meanwhile, in Central Park, a young man in a prison uniform gets impaled on a tree.

There are different kinds of pain.

While Castle gets acquainted with his new house assistant, “Lucy”, a cybernetic pyramid that seems like a total throwback to Her, he is given the idea by the inanimate object that the way to win his wife back is to get her to fall in love with him again, just like she did the first time.

The game is afoot.

The 12th Precinct are on hand for the grizzly murder scene, scanning through prison records looking for escaped convicts as the victim wore a prison jumpsuit. Lanie, Espo and Ryan try to work out details of the break up and why Beckett needs space.

Only she and new Digital Investigator, Vikram, know the answer.

He is hot on the trail of a ghost, while Castle is hot on the trail of a lead.

After visiting Lanie in the morgue, Castle spots his red devil tattoo and realises he’s a frat brother at Hudson University. He offers himself as a guest lecturer to get closer to the potential killer, and Alexis poses as a student in the class to smoke out the top suspect. Javi and Ryan try to “Jump Street” him, but that didn’t work and was very hilarious.

They discover the victim’s secret sex dungeon, where he engaged in a BDSM affair with a mystery person. Alexis goes undercover at the frat house for a party, and Castle freaks so joins in as a Beer Pong opponent. He gets some info on Peter’s lady love when Beckett arrives, shuts the party down and calls him a lightweight.

Ah, true love.

They track the cell of Peter’s psych professor — the one with whom he is reportedly having an affair — to an abandoned building across town. They discover that there is a secret prison experiment, reminiscent of the Stanford Prison Experiment, taking place that Peter was part of and is the reason why he was wearing a prison uniform.

Castle takes the professor under citizen’s arrest after talking to Peter’s neighbouring cell mate about the psychological torture they undergo daily.

He takes her to the precinct and Espo and Ryan follow him to the fake prison, which has been cleared since they were there last.

The professor is adamant she was not sleeping with Peter but informs Beckett the Dean was.

Castle and Beckett visit the prison together, and sparks fly –particularly after Castle locks them in a cell together. He asks if she felt trapped in their marriage. She said no, and she just needs some time. They find out Peter’s escape route was through the ceiling fan and that he must have had an accomplice.

Saying that, I find it very hard to believe they could get up to the ceiling when Beckett had to stand on Castle’s shoulders, and they were hindered by separate cells.

I digress.

Peter’s next door cellmate is brought into the precinct, as she murdered him. The psychological games got to her, and, after she left, the anger took over since he got a fellowship for college and she didn’t, but she could not understand why she killed him.

It’s possible to push people over the edge.

Castle and Alexis celebrate another case solved with a bubble cigar (Castle P.I. offices really have everything, don’t they?), and Beckett moves forward with hunting down her mystery killer by tracing the route of Vulcan Simmons drug stash.

So PopWrappers: thoughts?