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'Star Trek: Discovery': Explaining the link to classic Trek

The Discovery boldly goes into classic Star Trek territory in new episode "Despite Yourself." Here's everything you need to know. Beware spoilers!

Richard Trenholm Former Movie and TV Senior Editor
Richard Trenholm was CNET's film and TV editor, covering the big screen, small screen and streaming. A member of the Film Critic's Circle, he's covered technology and culture from London's tech scene to Europe's refugee camps to the Sundance film festival.
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Richard Trenholm
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" Star Trek : Discovery" is back with the new episode "Despite Yourself", and the crew members of the USS Discovery have gone through the looking glass.

This mid-season premiere sets up the second half of season 1 with the Discovery taking a new direction, based on some much-loved Star Trek lore. With heavy spoilers, we explain the show's big links to classic Trek so you're up to speed as the show heads into a new reality.

After last year's mid-season finale, the Discovery is stranded in unfamiliar space. Michael Burnham and Captain Lorca are ready to take the war to the Kingons, but Lt. Stamets is incapacitated and unable to operate the ship's space-hopping spore drive. Lt. Tyler is struggling with traumatic flashbacks to his torture at the hands of the Klingon L'Rell, leading him down a dark path as he tries to hide his growing dysfunction.

With the Spore Drive offline, the Discovery crew must make themselves at home in a bleak alternate universe in which dark, xenophobic versions of themselves make up the fascist Terran Empire. Yes, Discovery has jumped into the Mirror Universe, a twisted parallel reality peopled by evil versions of our heroes.

We've made multiple visits to the Mirror Universe through Trek history. The fiendish alternative reality first appeared in "The Original Series" in 1967, in season 2 episode "Mirror, Mirror". Captain Kirk and the crew of the Enterprise met and swapped places with their own ruthless, murderous counterparts in the Terran Empire, complete with revealing costumes, evil goatees and daggers never far from reach.

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As well as providing the setting for various spin-off comics and novels, Star Trek returned to the Mirror Universe on screen in "Deep Space Nine", but it's the prequel show "Enterprise" that's most relevant to "Despite Yourself".

The 2005 two-part story "In a Mirror, Darkly" was set entirely within the dark dimension. It involved the Federation starship USS Defiant, a contemporary of Captain Kirk's Enterprise, which was zapped from the main Star Trek reality in another TOS episode, "The Tholian Web". Not only did it end up in the Mirror Universe, it also went back in time to the "Enterprise" prequel era, making its advanced technology a valued prize for the warlike Terran Empire.

By the way, if the name sounds familiar, this isn't the Defiant seen in "Deep Space Nine". It's a TOS-era Constitution class ship, similar in design to Kirk and co's original Enterprise. 

Wow, that's some heavy continuity...

Don't worry, all you need to know is that the Defiant is a ship from regular Star Trek that ended up in the Mirror Universe before the Discovery arrived. The crew of the Discovery set out to find the Defiant to figure out a way home.

Will they find it? The Defiant was last seen commanded by the Mirror Universe version of "Enterprise" character Hoshi Sato, who used the Defiant's superior technology to declare herself Empress of the evil Terran Federation. By the time the Discovery crew arrive in "Despite Yourself", the Emperor's identity is shrouded in secrecy, but we're willing to bet we'll encounter this ruthless ruler in coming weeks. Any guesses who the Emperor might be?

This second part of "Discovery" season 1 continues on paid streaming services CBS All Access in the US and Netflix elsewhere. (Disclosure: CBS is CNET's parent company.) 

Here are some more questions we hope the new episodes will answer as the crew head deeper into the Mirror Universe and beyond.

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