Actually, there isn’t too much of a reason. Officially, the detectives have to solve a cold case from the 1970s with a key witness who thinks it’s still 1978. They re-create the era in costume and attitude so that the guy won’t shut down with psychological trauma.
Mostly, however, this is an excuse to dress the “Castle” characters in ludicrous garb from the disco age. It’s fun and it’s silly, and that’s really the reason for all of this.
Unlike disco, polyester never dies
Construction workers find the bones of notorious ’70s crime boss Vince Bianchi during demolition, touching off the coldest of cold cases. The assorted group of mobsters and molls most likely to be guilty are now shuffling toward retirement, and the star witness — Bianchi’s righthand man and consigliare, Harold Leon — is pretty much senile.
Interviews with multiple aging members of crime families don’t yield much in the way of results. The only real clue is a powder-blue, polyester suit (of course) that proves Bianchi went out to meet some unknown person on the night of his death.
Unlike Bianchi and the minds of all concerned, the suit is still in good shape in the present day.
If you had to get stuck in a decade, would you really pick the ’70s?
Castle and Beckett go to visit Harold for information, but neither the man’s head nor his home would count as normal. Everything in the guy’s life — from clothing to television programming — has remained in the ’70s. The mere mention of time’s passage creates all sorts of confusion for the guy.
He’s also a bit scared of reprisal, should he be caught talking to the cops about Bianchi’s death. Because of this, Harold will only talk in the precinct. And Harold will only talk at all if he thinks it’s the ’70s.
Enter Martha: Thwarted in her attempts to create a royal wedding for Castle and Beckett, Martha channels her energies into turning back time with costumes, makeup and actors. The results are, in short, amazing.
They also yield important information from Harold.
Probably not the twist you were expecting
Despite all appearances, Harold actually pops into the present at some point in the investigation, and his extreme grief yields an explanation — Vince and Harold were lovers back in the day. This was far from being an acceptable lifestyle for someone in the mob, of course, so Bianchi planned to marry a rival’s sister — now the wife of a former rival Frank Russo — to help solidify his power and to hide his secret.
That proved to be Bianchi’s undoing, though. He was supposed to propose to the woman on that fateful night but eventually couldn’t go through with it. Enraged that Vince would turn her down in favor of someone else, she took her would-be fiance out.
The scorned woman got her brother to bury Bianchi into the foundation of a building and married another mobster for power. Years later, she even tries to have Harold gunned down to keep him silent.
At least now that the real murderer has been caught, maybe Harold can move into another decade. Disco, after all, is very dead.