WARNING: The following contains spoilers for Star Trek: Discovery Season 4, Episode 3, "Choose to Live," streaming now on Paramount+.
While the United Federation and Starfleet continue to rebuild themselves after recovering from the cataclysmic event known as the Burn, the resurgent organization is threatened by a powerful gravitational anomaly that defies all known science and analysis employed by the crew of the USS Discovery. And while the anomaly has already claimed friendly civilizations in its inescapable maw, Starfleet has a different crisis to worry about as its shipments of dilithium to its restored allies is targeted by especially lethal individuals.
As the USS Credence arrives to deliver a shipment of dilithium to a civilization reentering the United Federation, they are boarded by a trio of hooded figures. When one of the Starfleet officers refuses the thieves' plea to stand down and choose to live rather than die fighting, he refuses and is brutally stabbed before the thieves leave with the dilithium. Reviewing the surveillance footage of the incident sometime later with Michael Burnham, Federation President Rillak and Ni'Var President T'Rina, Admiral Vance observes that this is the fourth such dilithium heist since the Federation began actively rebuilding itself, and the first that resulted in the murder of a Starfleet officer. Vance identifies the lead culprit as a citizen of Ni'Var, the reunified and renamed Vulcan-Romulan homeworld, leading a crew of mercenaries. Anticipating the heist, Starfleet planted a tracker in the dilithium which has provided them with the thieves' presumed coordinates.
With Ni'Var being such an important ally and prospective full member to the Federation once again, this sensitive matter leads to the Romulan warrior nuns the Qowat Milat being involved, headed by Burnham's mother Gabrielle as the thief was a former sister. Gabrielle and T'Rina vow to bring in the culprits alive, with Rillak proposing they make the assignment a joint mission with the crew of the Discovery as a gesture of goodwill and as Starfleet has a vested interest. Privately, Rillak informs Burnham that while Ni'Var's pending induction into the Federation is crucial in dealing with the anomaly due to their keen scientific minds, the culprits must also be brought into Starfleet custody, a condition to which Burnham readily agrees to.
Reviewing data of the anomaly with Burnham, Paul Stamets theorizes it is a primordial wormhole due to its cosmic properties and, more accurately, dubs it a dark matter anomaly based on this analysis but still finds its behavior completely unpredictable. Stamets presents this data to the Ni'Var Science Academy, but the scientists are unconvinced by the findings, with T'Rina instead suggesting she mind-meld with Book to reveal more about the anomaly. Book agrees, though this effectively has him relive the memories of Kwejian's destruction and yields no new information. Back on the Discovery, a Trill Guardian guides Adira and Gray to unjoin from their connection through the Tal symbiont so that Gray's consciousness can inhabit the synthetic body Doctor Hugh Culber has prepared for him, but the procedure does not come without its own set of risks. Fortunately, it ultimately results in success.
Saru recommends Sylvia Tilly to join Burnham on the mission with the Qowat Milat due to Tilly's warming presence and Tilly needing a little personal guidance, to which Burnham and Tilly happily agree. As the detachment nears the thieves' hideout on a remote moon in a separate, smaller vessel, they are ambushed and Gabrielle's Romulan sister is murdered by a group of thieves boarding the ship. Beaming down after their leader, the landing party finds the moon to be home to apparently dead civilization and the thieves using the dilithium to power the moon as a mobile planetoid moving through space before they realize the entombed aliens are in cryostasis en route to a new homeworld.
The thief ambushes the landing party and holds Gabrielle at swordpoint, revealing she stole the dilithium to keep this species alive but had to keep their existence a secret as their pods are laced with valuable latinum, a substance that attracted grave robbers putting them on her radar. While Tilly repairs the moon's engine, Burnham investigates how to fix the cryostasis system as the species revives to settle on the new homeworld they set out for long ago. With the species guaranteed a new chance at life, the warrior nun surrenders to Starfleet before being remanded to Ni'Var custody in a continued show of goodwill, a move that frustrates Burnham, who wants more punitive justice, but one she accepts as she reunites with a recovering Book back on the Discovery.
To see Starfleet take on these thieves, Star Trek: Discovery Season 4 is streaming now on Paramount+, with new episodes released on Thursdays.