A vessel flies through space. It is Federation HQ, heading to evacuate Earth. Onboard, Tilly is instructing the cadets on how to organize the evacuation.

Vance informs Tilly they have four hours left. The cadets ask how many can be saved and Vance admits it’s only about a million combined.

On Discovery, Hirai is still asking Ten-C to release them from the orb. Tarka is accelerating towards the DMA power source. The Ten-C release more orbs to try to catch Book’s ship. Burnham asks Rillak to join her when she orders all the diplomats to be confined to quarters.

Tarka manages to evade the orbs. In their confinement, Book finds something that might help him and Reno escape.

As they wait for the diplomats to gather, Ndoye admits to her part in Tarka’s escape from the orb. Burnham informs her of the consequences of her actions and has her confined to quarters.

The Ten-C respond to the request for release by telling Discovery they are already free. T’Rina offers to link with the Ten-C telepathically. She links but it overwhelms her. She survives and is able to tell the others that the Ten-C are confused and frightened and no longer trust them.

While recovering in sickbay, T’Rina explains that her link wasn’t with one Ten-C but all of them. They have no concept of individuality.

Stamets alerts them that he has a way out of the orb. Saru takes a moment to speak with T’Rina about the emotional risks of being close to someone else.

On Book’s ship, Tarka announces that in fifteen minutes, it’ll all be over. He offers to take Book with him to the other dimension where Kwejian would be unharmed. Reno points out a replacement wouldn’t be the people and planet he lost. Book agrees.

Stamets’s plan requires them to burn out the spore drive in order to break out of the orb. Warping home would take decades.

Book uses one of Grudge’s cat collars to open a cat door in the force field trapping him and Reno.

Stamets’s plan works, damaging Discovery but freeing them to pursue Tarka.

Book knocks out Tarka but he and Reno are locked out of the ship’s systems. He gives Reno his badge and has her beam back to Discovery. She delivers his message to Burnham. Rillak suggests bringing in Ndoye to consult on a plan. They have less than ten minutes before Tarka destroys the DMA controller.

Back at Earth, debris is coming in from the DMA.

Ndoye suggests a targeted hit by a piloted shuttle. Burnham is about to call upon Detmers but Ndoye volunteers.

The DMA debris knocks out the Federation HQ’s propulsion systems. Vance orders everyone to cease evacuation efforts and depart Earth and the moon immediately. He orders abandon ship. Tilly and him are the last left aboard.

On Book’s ship, Tarka wakes up and Book gets through to him but he set up the system with an encryption key so no one, not even Tarka, can stop it.

The proximity alert sounds. Ndoye’s shuttle hits Book’s ship, disrupting the beam cutting through the DMA casement. Owosekun beams Ndoye back to sickbay. On Book’s ship, Tarka cuts life support to free up enough energy to beam Book to Discovery. Tarka prepares his interdimensional transporter and waits for the impact with the hyperfield.

Book’s transport signature starts to come through but his ship hits the hyperfield and the signal is lost. Burnham mourns the loss. The Ten-C sends another orb. She prepares to meet them.

Tilly and Vance sit to wait out the last two hours, drinking Risan whiskey, ironically, a gift from Tarka.

The Ten-C’s orb takes Discovery into the gas giant, towards a massive structure filled with thousands of life signs.

The Ten-C send a message conveying their understanding of their individuality. They will send transport so they can join them. Burnham orders everyone to the shuttle bay to be a part of the moment. They are brought to the surface of the planet. Stamets and Adira stay on the ship to coordinate with Zora so they can continue to communicate with the Ten-C.

Burnham and Rillak explain to the Ten-C about Tarka and Book’s attempt to destroy the casement and how the DMA destroyed Book’s world and how it is about to destroy Earth and Ni’Var. The Ten-C move the DMA away.

The Ten-C ask about Burnham’s sadness. She explains about losing Book. They restore him to her. Book asks to address the Ten-C.

He asks if the DMA is gone for good. They reply that they will scan more broadly for life before mining areas of space. Book says that’s not enough. The DMA destroys lives and leaves behind a toxic field. The Ten-C need the DMA to keep their hyperfield functioning. Book argues that their fear is no way to honor those that they have lost.

His empathic powers activate and the lights show on his forehead. The Ten-C all reflect back the same light pattern. They send a new message, vowing to make right the wrongs they have caused.

Tilly and Vance celebrate the mission’s success as the debris field retreats from Earth.

Onboard Discovery, the crew watch as the hyperfield comes down. The DMA wormhole reforms and approaches Discovery to send them home.

Back home, Tilly and Vance join the crew as they recuperate and relax.

Saru seeks out T’Rina.

Rillak and Burnham talk.

Burnham and Book talk. His sentence from the Federation is to help with families displaced by the DMA.

United Earth’s president, played by Stacey Abrams, meets Rillak and declines negotiations. United Earth is all in.