A routine repair mission for the U.S.S. Shenzhou turns up a mysterious artifact, and First Officer Michael Burnham's decision to investigate sets her crew on a path toward volatile conflict with a Klingon warship.

When the Klingons orchestrate a shooting war with Starfleet the Shenzhou finds itself front-and-center. In the wake of the battle Captain Georgiou and Commander Burnham find a way to strike back at the enemy.

Burnham is brought on board the U.S.S. Discovery by its enigmatic Captain, Gabriel Lorca, who tasks her with helping the engineering team. But after a catastrophe leaves Discovery's sister ship adrift, Michael is ordered to join a dangerous away mission.

Burnham is tasked with studying the creature retrieved from the Glenn to aid in the war, while Discovery must fly to the aid of a Federation mining colony under attack. At the binary stars Voq tries to get T'Kuvma's ship up and running, but faces a difficult challenge.

Captain Lorca is abducted and finds himself on a Klingon prison ship, with Harcourt Fenton Mudd as a cell mate. As the Discovery enters enemy territory in search of their captain, Saru and Burnham clash over their continued use of the tardigrade.

After Sarek is gravely injured in deep space Michael uses their telepathic connection to try and find him -- facing the demons of her own past along the way. Admiral Cornwell's visit to Discovery leads to a confrontation with Lorca.

Harry Mudd traps the Discovery crew in a 30-minute time loop, boarding the ship in an attempt to learn its secrets -- and sell it to the Klingons for a profit.

Saru, Tyler, and Burnham visit a world with a natural crystal formation they hope they can use to expose the Klingon cloaking technology, but find an evidently sentient life form unlike any they have encountered. Elsewhere L'Rell returns to the sarcophagus ship with an offer to interrogate Kol's Starfleet prisoner.

The Discovery crew acts against orders to lay a trap for the Klingon sarcophagus ship in a desperate gambit to use the spore drive to overcome the enemy's cloaking technology. Lt. Tyler has a personal crisis when he comes face-to-face with his former captor.

The crew of Discovery find themselves stranded in a parallel universe, where their only chance of survival is to emulate the hostile Terran Empire. As Ash Tyler continues to struggle with his past trauma, Dr. Culber tends to a patient left mentally broken by their recent journey.

Burnham defies orders to destroy a Resistance cell in order to meet with them face-to-face instead -- only to see Tyler break in front of her eyes. On Discovery, Tilly works desperately to restore Stamets' mind.

Burnham delivers Captain Lorca to the Emperor of the mirror universe in an attempt to recover vital information, bringing her face-to-face with a haunting figure from her past. On Discovery Saru makes an appeal to their prisoner, while Lt. Stamets finds himself trapped inside the mycelial network with his other self.

Lorca launches an all-out coup against the Emperor, putting Michael and her loyalties squarely in the middle -- while Discovery weighs a desperate gambit to restore the mycelial network that may cost the crew their lives.

Admiral Cornwell hopes that Discovery's return home might reverse the tide of war with the Klingons, with Starfleet's newest strategist recommending an assault on the enemy home world. While Stamets hatches a plan to restore their crop of spores, Burnham must confront Lt. Tyler.

The Discovery crew is forced to follow a leader they do not trust on a mission to infiltrate the enemy homeworld Qo'nos and identify key military targets -- but Burnham, Tilly, and Tyler soon discover that a desperate Starfleet may be selling its soul in the process.