Burnham's working on a memory tree of her own, inspired by the Akaali's lalogi orb. Book comes in to discuss the next mission. He mentions that it would've been his father's birthday today.

Discovery is heading into the subspace rift. Book wants to find new leads by jumping out of Federation space. Burnham argues they should stick to the plan.

Saru and Burnham discuss the history of Starfleet ships flying into subspace rifts. They expect a bumpy ride.

In the turbolift, they chat with Zora about her emotional development.

All crew are called to stations. This interrupts Adira and Gray's board game. Adira is taking Linus's position for the day. Gray's left alone as everyone else is working.

As they enter the rift, they experience the expected space turbulence. Suddenly, everything is calm. Detmers has no nav readings so she can't confirm their location. All they can see is a dark void.

Book's sensors read nothing as well. He's eager to do recon but Burnham insists they send a Dot first.

As the Dot gets further away from the ship, it stops responding to commands and begins to disintegrate. It makes a sound like screaming.

Adira hypothesizes the DMA has turned subspace toxic.

When they send a flare out, they're able to tell the edge of the DMA toxicity is getting closer to the ship.

Book joins Stamets in Engineering.

Gray and Zora discuss the events in the rift. He wants to help. Zora explains how her sensors are not reporting in the normal way. Gray offers to play a game with her to help clear her head.

After discussion with Saru, Burnham orders them to abandon the mission. Detmers is unable to chart a course out of the rift. Book offers to jump while Stamets monitors the data.

The jump doesn't work. Feedback zaps Book. Stamets reports there's something wrong with the mycelial network.

Book stands up and sees his father. His father berates him for not hunting whoever destroyed their planet. Stamets gets Book to sick bay.

Book tells Burnham about seeing his father. Stamets proposes they study the energy that surged through Book to learn about the void and the DMA.

Zora detects an issue on Deck 17. Burnham sends Dr. Pollard. She finds a hull breach. The ship sets a containment field which traps a crew member who gets sucked into the void. Gray realizes Zora's external sensors are getting some information.

Multiple parts of the ship are thinning. Gray reports to the bridge and Zora explains how she was able to detect the breach before it happened.

Saru figures out a way for Zora to get them out of the void but it'll need brainstorming by the crew.

Book continues to be harassed by his father.

On the bridge, Owosekun offers to help reinforce Engineering but Saru gives an order to keep her at her station.

In the ready room, Zora admits to being afraid of the void. Burnham talks her through the feelings.

Burnham is called to sickbay where Stamets and Culber share that the energy particles in Book's brain are only found in the Galactic Barrier.

They program the particle and the bridge crew realize they can use sonar to find the puncture point from which they can exit.

They find the ping but it's too far away for them to get out before the ship superheats. Burnham suggests the crew hides in the pattern buffer for the time it takes Zora to get them out.

Book goes to get Grudge and finds his father on his ship. He says goodbye to his father. He takes Grudge to wish Michael good luck.

Burnham prepares to ride out the rift with Zora.

The conditions on the bridge exceed safety parameters and Zora sings Burnham a song as she prepares to die.

Burnham survives.

Book and Saru discuss the investigation's next move and their own respective personal rages.

Zora creates her own tree for Burnham. Burnham recognizes the ship's uniqueness.