10 Most Rewatchable Star Trek: Deep Space Nine Episodes

By the middle of Deep Space Nine's fifth season, the show's creative team decided to raise the stakes in the Federation-Dominion cold war. That lengthy buildup paid off with this wonderfully tense two-parter that shook the fabric of not only the station's crew, but also the entire Alpha Quadrant. "In Purgatory's Shadow" and "By Inferno's Light" turn several characters on their heads, challenging previous perceptions and leaving audiences wondering what clues they missed along the way. This staggering episode continues to shock with each viewing, yet remains among Deep Space Nine's most exhilarating rides from start to finish.

The episode's showpiece is Internment Camp 371, where Garak and Worf get locked up by the Dominion after following a coded message from ex-Obsidian Order leader Tain. That's right, him again.

Along the way, audiences finally meet the real General Martok, whose Changeling counterpart was revealed in season opener "Apocalypse Rising". In the episode's next big twist, Garak and Worf reunite with Dr. Julian Bashir, whose doppelgänger is busy running amok back home.

There's also a secret Jem'Hadar fleet threatening the Alpha Quadrant, Tain finally admitting he's Garak's father, and the Cardassians joining the Dominion. Who can even keep all this stuff straight?

The point is that by the time Garak, Worf, and Bashir manage to escape and return to the station, almost everything they've known has been changed forever.

"In Purgatory's Shadow" and "By Inferno's Light" proved that Deep Space Nine was still full of surprises, even five years on. Between the sheer jolt of learning Bashir was replaced with a Changeling and the betrayal of watching Dukat sell Cardassia to the Dominion, good luck turning away from this one. Its mysterious, frantic tone sucks you in and always leaves you eager to return. With the Dominion now firmly entrenched in the Alpha Quadrant, nothing would ever be the same again. Thank the Prophets for that.