The ships approach the planet-sized library archive. The doctor thinks about the last time they were there. The first time was to find a cure against a flesh-eating fungus in their solar system. The second time was to let their mother pass. Now, the library, an archive of infinite knowledge, has resigned itself to destruction. An unconfirmed rumor at first, soon word got around that the library’s end was official.

The doctor talks to his assistant about the matter. The assistant used to be a representative of the doctor’s system, but now they’re an ambassador for the library. Upon hearing about the library’s impending destruction, everyone has been whipped up into a frenzy and has been trying to tell the library to live. The doctor says that the library must live for the good of all knowledge, but the assistant says that the library, as a sentient thing, should have the freedom to decide its own fate, even its own destruction. The assistant then asks them if they want to come down to the library’s celebration, at least to meet his children. The doctor thinks about how, at a young age, they medically terminated their ability for birth, as they knew child-birthing wasn’t for them. Still, they’re excited at the thought of seeing their assistant’s children.

At the festival, the doctor and assistant traverse all sorts of stalls and move through crowds of people. They pass by a stall of edible mushroom, the kind which they designed. The doctor, angrily, wonders how everyone can be so calm despite what’s going on. Together, they go to have a sandwich. The doctor thinks about how, a long time ago, they were facing a blight of native flowers in their solar system, prompting the doctor and his crew to go to the library and find a solution. Their attempt at a cure failed, however. Now, the doctor and their assistant go to an amphitheater and watch a performance. The doctor still can’t let go of the library. The assistant explains that it’s become lonely after millions of years. Angrily, the doctor storms off.

In their cabin, the doctor sweatily tries to sleep. They wonder again why everyone is so calm. They think about their first visit to the library. Back then, they go to the library and realize that it’s sentient and alive, more so than other planets. They don’t have to wear suits on it, as it has its own atmosphere and won’t contaminate them. On the ground, they land in a forest, and the trees respond to their touch and transform at will. There, the doctor and their crew start to gather samples and wonder why they don’t need protective gear despite all that’s going on.

A voice tells them that the fungus is only harmful during ingestion. It addresses the sample which the doctor and their crew sent in, which has been genetically modified somehow. It says that the species in the library’s forest can use the sample as a disposal method. The doctor and their crew ask what the species is. Already, they know way more about the fungus than before. Soon enough, the doctor realizes that the planet has been able to get inside of their heads. They wonder how powerful it is and what it can really do. After they leave, on their ship, they watch as the library completely transforms itself from top-to-bottom.

The doctor wakes up from their cabin and goes back out to the festivities. There, they see a hologram with multiple heads and faces. They see a timer, which says that the library only has seven hours left. The doctor intends to steal a shuttle to go to the library alone. They go to an abandoned shuttle but are momentarily stopped by two guards. Quickly, however, the doctor tells them that they’re the doctor and that they just want to get on a shuttle to visit their neighbor. Realizing that they’re the doctor who cured a certain virus, the guards let them through and tell them to be back before the timer hits four hours. They head onto the shuttle and land onto the library.

The doctor remembers the second visit. There, the doctor takes their dying mother there, bringing her down onto the library which has become a forest of singing plants again. Their mother has been dying ever since the fungus has spread, faster than they were able to find a solution to it. Now, the singing plants erupt and fill them all with sound. The doctor’s mother cries tears of joy, as pain leaves her body, until she passes. Still, as the doctor and their crew leave the library again, they still hear the sound of the singing plants.

On the library for a third time, the doctor cries out loud and begs for a piece of their mother back. There’s nothing. Floating above in the library in their ship now, they watch as it blinks out of existence just like that.