Michael is stranded after her jump 930 years into the future, and with no sign of Discovery is forced to trust a courier working for a syndicate of Orions and Andorians in a galaxy where the Federation has fallen.
After Discovery crash-lands on an icy planet the weary crew attempts to effect repairs, while Saru and Tilly's attempt to contact the local miners puts them in the middle of a tense situation.
Reunited with their lost comrade, Discovery jumps to Earth — only to find that their home has become isolationist. While a group of inspectors board the ship, a new conflict brews with raiders in search of dilithium.
After finding a human hosting a Trill symbiant, Discovery brings Adira to the Trill homeworld in hopes of unlocking the memories of her previous host – including what happened to the Federation. Saru tasks Stamets and Tilly with building a new interface to operate the spore drive.
Discovery arrives at Starfleet's thirty-second-century headquarters, and Burnham seeks a way to prove themselves to an Admiral who remains suspicious of them — and intent on reassigning the crew.
Burnham and Georgiou act against orders to go in search of Book, who has become a slave laborer on a salvage planet run by Emerald Chain — where he says he has found a "black box" that survived the Burn.
A new revelation sends Burnham home to Ni'var — once the planet Vulcan — where Discovery plays host to Vulcans and Romulans in an ancient ritual that stands between them and secrets about the Burn.
Discovery places itself in a tense standoff with the Emerald Chain leader, Osira, when they travel to Book's homeworld of Kewjian – where Osira intends to recapture the escaped workers from Hunhau.
To try and save Georgiou's life the crew brings her to an uninhabited world on the edge of the galaxy, where a mysterious stranger gives her an opportunity to revisit her troubled past.
Having returned to the Mirror Universe, Empress Georgiou attempts to convert Michael to a new way of seeing things — and must come to terms with how she herself has changed, too.
When Discovery attempts to rescue a solitary survivor inside the deadly Verubin Nebula, Saru, Burnham, and Colber transport into a holographic simulation left behind by the Kelpian survivor's mother.
As Saru and the away team attempt to lead Su'kal to reconcile with his past, Burnham leads Discovery's skeleton crew in an effort to retake the ship from the Emerald Chain.
