2.01: A Stitch in Time

[Brit Chick]

No idea which season this ep was from - but it was a fantasic story. it starts off with FBI agent Jamie Pratt (Ensign Ro from DS9) investigating the deaths of seventeen men in different parts of the country - all murdered with apparently the same weapon BUT the kicker is that its a gun that wasn't made till the mid 80's and these murders started in the 50's !! turns out to be a physics professor with a time machine and a big time grudge and all the guys she goes back and kills were serial killers.

I won't go into the twists and turns too much in case anyone wants to see it - the info above is evident in like the first 5 mins so its not really a spoiler, just enough to get people like me interested in watching it. It you ever see it listed try and watch it.