Tipped off my Bobby's old friend Sheriff Jody Mills (Kim Rhodes), the Winchester brothers find themselves chasing a creature that is draining life energy from its victims.
However, when Dean tackles it in an alleyway, he and the creature are transported back to 1944. Dean is promptly arrested by the police, but then sprung by a hunter from that period... Elliot Ness (Nicholas Lea).
Meanwhile back in the present Sam and Sheriff Mills discover that the creature is actually the god Chronos (Jason Dohring), God of Time, but then have to figure a way to get Dean back from the 1940s.
I've always been slightly uncomfortable with time travel stories in Supernatural, as they don't really seem to gel with the show's verisimilitude, but so far the writers have always found a way to put a special Supernatural spin on them.
Time After Time has the clever angle of Sam and Dean working the same case in two different time periods, but does little to get over the pointless silliness of making Elliot Ness a hunter. That's only a small step away from saying that Abraham Lincoln: Vampire Hunter is part of the Supernatural universe as well.
For me one of the strengths of Supernatural has always been that its heroes - the hunters - were just anonymous, working class stiffs. To suddenly reveal a famous, historical personage was really a hunter of monsters and demons strains the Truth of the show just a bit too far for my liking.
And, except for giving Dean a reason to keep quoting The Untouchables, having Lea's character be Elliot Ness made no difference to the story at all. In fact, it was a distraction because you couldn't help but keep mentally trying to make this gel with the known facts of the prohibition agent's life.
Lea, well-known as Alex Krycek from The X-Files, could easily have been any federal agent of that period and Dean could still have tried to emulate Sean Connery from The Untouchables.
I just can't understand what possessed Robbie Thompson, who also wrote the excellent Slash Fiction, to use Ness or why the production team allowed it to go ahead... except possibly for cheap laughs. In reality all it does is pull the rug out from under an already quite mediocre episode.
And since when does an experienced hunter tackle an unknown monster by running at it and jumping on it?
One of the saving graces though of Time After Time is the addition of Sheriff Mills to the growing Winchester family, now that she's fully au fait with what they do and can use her police contacts to help them out. I know she doesn't return this season, but I hope a place is found for her character is season eight.