Aboard his ship, Cleveland Booker sits quietly and remembers flying through a flock of falling birds shortly before the destruction of Kwejian. He also sees Kyheem and Leto, who were on the planet when it was destroyed by an anomaly. Captain Michael Burnham attempts to comfort him, but is called away by the arrival of a guest. Booker, otherwise unresponsive, urges her to go.
In her ready room, Burnham greets Saru, who again wears a Starfleet uniform. She tells him Booker is the only known survivor from Kwejian, though Starfleet is looking for others of this species who may have been offworld. Burnham also reveals Booker has been numb from grief in the two days since Kwejian’s destruction. Saru explains that he will remain a village council member in absentia but that Starfleet needs him now. Burnham congratulates Saru on being offered command of the USS Sojourner. Saru replies that while he one day would like to return to the captain’s chair, “this is not that time.” He offers to serve as a second pair of trusted eyes to Burnham, as she did for him when he first became captain.
In a briefing at headquarters, Commander Paul Stamets explains that the anomaly that hit Kwejian and Deep Space Repair Beta Six is a massive five light years in diameter, shocking Federation President Laira Rillak. Stamets and Lieutenant Sylvia Tilly explain they are flummoxed by the anomaly and that their current theory is that it is a roving binary black hole, two black holes that are merging and creating huge gravitational waves in the process. Kwejian was destroyed because it was closer to the source of the waves; the station, farther away, was able to survive its initial impact. Rillak asks why no one saw the anomaly approaching; Tilly responds that black holes are largely undetectable unless debris is actively falling into them. Stamets brings up holographic simulations based on their theory that seem to account for what happened to Kwejian. Just then, Booker enters the room, creating an awkward atmosphere. He asks them to continue. The simulation shows the destruction of Kwejian; no planet could withstand such stresses.
Their models indicate the anomaly will enter the Riscot system soon, and Rillak orders an immediate evacuation. Other Starfleet captains have numerous questions, but Burnham says the only way to find answers is to collect more data. Ni’Var President T’Rina offers the services of the Ni’Var Science Institute in analyzing any data, explaining that while Ni’Var is not a Federation member, such a crisis requires contributions from all allies. T’Rina also warns of potential civil unrest.
Aboard USS Discovery, Tilly acts awkwardly while walking down a corridor with Saru. She asks if he has gotten taller. Saru says he has not, and Tilly posits he has more “swagger,” which she assures him is a compliment. Tilly shares her discomfort in the wake of the death of Cmdr. Nalas and the destruction of Kwejian, marveling at her smallness in the cosmos. But Saru argues that how each individual spends their time matters.
They arrive on the bridge, where Lieutenant Commander Joann Owosekun addresses Saru as captain. He asks to be addressed simply as Saru, but Burnham suggests instead “Mr. Saru.” Speaking on a shipwide channel, Burnham tells the crew about the danger they face in investigating the anomaly and vows to prevent further deaths. Discovery uses its spore drive to jump close to the anomaly. A polarizing spectrographic filter on the viewscreen reveals the anomaly, unnerving the crew.
Lt. Cmdr. Keyla Detmer keeps Discovery at a safe distance from the anomaly, but Owosekun reports the subspace gravitational waves are not what they had predicted. They also are unable to see two black holes, potentially discounting their working theory. Tilly explains that there is an accretion cloud made up of gas, dust, and large amounts of dark matter surrounding a gravity well, so a black hole still fits. However, Stamets says, the gravitational doppler shift from their scans is “way off,” leaving them perplexed. The ship’s scanners cannot penetrate the outer edge of the accretion cloud. Obtaining the necessary data will require flying into it, which Detmer warns would pose a serious risk to Discovery. Saru suggests sending DOT drones with sensors, but maintaining communications would be difficult. Booker offers up his ship, which is large enough to navigate the cloud but small enough to avoid most of the debris. It can also change shape to compensate for torque. Burnham orders Detmer and Stamets to prepare to go in, but Booker asks to speak in private.
Burnham tells Booker that the pilot must be clear-headed. Booker pushes back and they fight, but ultimately he notes that he is not a member of Starfleet and does not need Burnham’s permission. Collecting the data right the first time may give them crucial information that could help save other worlds, he argues.
In sickbay, Doctor Hugh Culber and Ensign Adira Tal show Gray Tal, still only visible to Adira, a holographic representation of his newly-constructed android body. Gray is excited for the possibilities of having corporeal form again, including becoming a host or becoming a Guardian. Gray feels guilty for feeling joy at a time of great sorrow, but Culber explains that life must continue. Culber notes the artist created an excellent likeness of Gray by using a Soong-type synth body, making Gray marvel at the eight hundred-year-old technology. Culber explains that transferring consciousness to synth bodies was tried many times after Altan Inigo Soong first successfully performed it on Admiral Jean-Luc Picard, but that a low success rate caused people to stop trying eventually. Adira and Gray are concerned; Culber replies that the survival of Gray’s consciousness to another host once was a good sign but says they can ask Guardian Xi once the synthetic body is ready. He also explains the body will age as Gray would have. Gray also asks whether a mole on his hand can be removed, explaining that during his first transition he had “bigger things to think about” but that he has a second chance to remake his body. Culber happily does so.
In her ready room, Burnham experiences a holographic recreation of Ni’Var – Vulcan – when she grew up there. Saru arrives and Burnham explains they are overlooking Lake Yuron, where Burnham would run away when she was getting used to her parents being gone. Burnham asks Zora to deactivate the hologram; the computer picked the name herself, Burnham tells Saru. She asks for his advice on Booker. She explains that as captain she believes him to be the right choice for the mission, but reveals that she has seen him struggling after the destruction of his homeworld. Saru suggests additional safety measures in case Booker should try to take an extreme risk.
In engineering, Stamets is shocked that Burnham has suggested sending him with Booker on such a dangerous mission, given they are the only two who can operate the spore drive. Burnham explains she will send a holographic projection of Stamets, keeping his body safe on Discovery, and maintaining a tether with Booker’s ship to maintain proximity and allow holographic signals to make it through the accretion cloud. She asks Culber to be on the bridge during the mission. Stamets confides in Culber that he doesn’t know what to say to Booker normally, let alone in the wake of Kwejian’s destruction. Culber recommends letting Booker guide him through his grief.
Stamets activates the transmitter and finds his holographic self standing next to a standoffish Booker aboard his ship. Trying to connect, Stamets awkwardly asks whether Booker feels cramps in his hands or tingles in his arms when using the spore drive, but Booker does not respond. Stamets goes to pet Grudge, but Booker warns against it as holos “freak her out” because she cannot smell them. He stows Grudge safely elsewhere. Booker expresses anger that Stamets is there as a “minder,” but Stamets insists he is there for his scientific expertise.
Booker and Stamets depart, tethered to Discovery.
They quickly impact large debris, which Stamets notes is likely because it just passed through a planetary system before realizing that system was Kwejian. As they pass through more debris, Booker is reminded of the falling birds on Kwejian just before its destruction and flashes back to images of Kyheem and Leto.
Meanwhile, on Discovery, a surprise subspace gravitational wave sends the crew flying into the air, where they remain suspended, helpless. Zora explains the artificial gravity generators cannot compensate, but the wave suddenly passes, sending the crew slamming into the deck and sparks flying from consoles. The crew is bruised but otherwise okay. Tilly remarks that Discovery should not have been affected.
Discovery was badly damaged, but the tether is intact. Booker’s ship loses navigation, but insists on remaining inside the accretion cloud to gather the needed data.
Tilly and Adira, who has cracked a rib, work to figure out why Discovery was so badly impacted. Adira feels Tilly is second-guessing their work, but Tilly snaps that in Starfleet, everyone’s work is double- and triple-checked. She also orders them to incorporate the new data on the irregular gravitational strain on Discovery. As Culber heals one of Tilly’s wounds, she confides that she feels she is “Stamets-ing” right now. Culber replies that Adira looks up to Tilly, which seems to unnerve her slightly. Adira returns with the updated calculations. They have just seconds to warn Burnham before another disturbance hits the ship, again sending the crew flying. Nilsson reports that another hit will destroy the artificial gravity generators completely, though Bryce suggests the hull may breach first. Tilly reports they have four minutes before the next hit, then one and a half minutes, then 40 seconds. She cannot explain the irregular pattern. Burnham mulls pulling Booker’s ship out, but Stamets is unsure whether he has collected enough data to answer critical questions and repairing Booker’s ship for a second effort could take a week. Meanwhile, Booker hallucinates Leto running around on his ship. His attention returned by Stamets, Booker recommends releasing the tether to keep Discovery safe, despite his loss of navigation. Burnham hesitates but orders the tether snapped and Discovery to retreat.
On Booker’s ship, Stamets still needs more time to finish his scans. The boson power unit emerges from the control panel, damaged. Booker directs Stamets to use a phase discriminator to repair it. Stamets objects to Booker’s terse tone, to which Booker replies that Stamets has spoken to him more today than in the prior five months combined. Booker accuses Stamets of having a bruised ego since he is no longer the only one capable of operating the spore drive. Stamets replies that he instead feels awkward around Booker because Booker saved Culber and Adira during the incident with Osyraa when Stamets could not. Just then, Stamets’ scans are complete. But he cannot transmit them to Discovery, or return his holographic consciousness, because of a communications block. The data now lives only on Booker’s ship.
On Discovery, Tilly and Adira have studied the anomaly and theorize that Booker could somehow ride one of the gravitational waves to safety. R.A. Bryce suggests adapting kitesurfing techniques he learned on Manark IV; accelerating into the distortion at a specific point would allow his buoyancy to carry the ship out. Without navigational sensors, Booker cannot simply guess the right angle and time, so Burnham will have to tell him when to go. Burnham waits for the right moment, but when she gives the order, Booker hesitates and they miss the wave. Stamets assures him another opportunity will come and that they have enough engine power for one more attempt. Booker is dejected, and tells Stamets to pull of the holotransmitter. “You’re not even here. No one’s here,” he says. Stamets replies: “I’m here. We’re all here.” Burnham warns of another distortion in two minutes, but Booker is distracted by another hallucination of Leto.
With Booker unresponsive, Saru urges Burnham to lean on her personal relationship to reach him. Using a private channel, including a protective shield around her command chair that prevents the rest of the bridge crew from hearing the conversation, Burnham insists that Booker could not have known about the danger and saved his family. Booker replies that he failed Kyheem and Leto, but Burnham says he did not, and promises that she and Discovery will not fail him now if only he trusts her. Calmed, Booker is able to guide his hip into the next wave with Burnham’s help. The bridge crew waits tensely for several seconds before Booker informs them he made it clear and begins transmitting data. Saru congratulates Bryce for using his specializes hobby knowledge. Tilly also praises Adira.
On Booker’s heavily damaged ship, Stamets formally thanks Booker for saving Culber and Adira. He promises to figure out the anomaly. Calling back to their earlier awkward conversation, Booker tells Stamets that he too feels tingling in his arms when operating the spore drive.
In a corridor, Tilly thanks Culber for his advice regarding Adira. She also tells him that she has felt off recently and asks for his professional help. Culber promises to help her figure it out and Tilly departs to begin parsing the data.
In their quarters, Gray congratulates Adira on their quick thinking. Adira tells Gray that Nalas’s death has made them think of Gray, who was similarly killed by a debris impact.
Booker tells Burnham that she was correct that he was not ready for a stressful mission. But, she replies, he succeeded by trusting her. He tells Burnham that he keeps seeing Leto and admits he does not know whether he ever revealed to his nephew how much he loved him, especially after finding his family again after being exiled for so long. Booker tearfully admits that Kyheem and Leto are gone.
On the bridge, Tilly reports to Saru that data analysis is in the early stages but that they have discovered a disturbing new fact: the anomaly changed direction while Discovery was nearby, explaining why the gravitational waves impacted the ship. They have no scientific explanation for what caused the change. More disturbingly, they will be unable to predict where or when it appears, leaving the Federation vulnerable.