Stargate SG1 Cold Lazarus
A mission off world leaves Jack alone on the planet when SG1 return to the SGC unaware the Jack that was accompanying them was an imposter. The crystals they retrieved from the planet have some unusual properties and they discover that they were struck by staff weapon fire and they crystals themselves are a manifestation of a sentient life form. Fake Jack however is out and about and armed with pictures of his dead son and family home returns and confronts his ex-wife and father in law. They are both concerned over Jack's apparent mental condition and when he convulses with energy rippling through his body he is taken to a local hospital, SG1 are now aware of the switch as the real Jack gated in and they confront the alien.
Cold Lazarus is a Jack back story I am not sure we really needed at least not for anyone familiar with the movie although we know his personal history is not common knowledge. There were some good moments as the alien in the form of Charlie was able to give some closure but that was kinda negated with the rather clumsy interaction with Sara played by Harley Jane Kozak. That said Teal'c got in some good lines and expressions in the episode and I did like the visuals of the alien world but overall an average season 1 episode.