As humanity prepares its final evacuation to the White Crystal Solar System, librarian Ms. Bookhart desperately searches for the final volume of a book series on Wipers. This volume will complete the knowledge repository being created for others to discover - the last human library. (Lesson: Overview of library/research skills and concepts.)
A century after humanity’s evacuation, the Users study Earth artifacts in search of a defense against the Wipers. They discover books, learning the differences between fiction and nonfiction books as well as how earthlings organized them. In search of more books a group of User children find Ms. Bookhart, placed in suspended animation by the mysterious Universal Being. (Lesson: Fact and fiction; alphabetical shelving.)
When they find the underground library in disarray after a Wiper attack, Ms. Bookhart shows the children about the different parts of books so that they can attempt to reconstruct the destroyed texts. Meanwhile, Chief Humbuckler plans to test the Wiper's jammers and magnetic shield on the User base. (Lesson: Parts of a book.)
Outside the User base, Colonel Holon makes contact over his communicator with the User children in the library, who attempt to use maps and the card catalog to find him a return route that avoids Wiper contact. Meanwhile, as Tesla exhorts her fellow Users that they will respond to the Wiper shield threat with reason and not violence, Humbuckler and the Wipers await the Users' eventual surrender. (Lesson:Card catalog.)
Colonel Holon encounters the Universal Being, who gives him a document. The User children must follow the clues given on the document and discover the means of defeating the Wipers. Meanwhile, when Tesla attempts to contact the children Humbuckler discovers there are Users outside of the dome and tells her that the Wipers will capture them. (Lesson: Dewey Decimal Classification System.)
As Colonel Holon evades a pursuing Wiper patrol he encounters horses, which frighten the the Wipers away. The User children make headway on deciphering the document's clues and Tesla ponders her options as power and food supplies dwindle inside the User base. (Lesson: Encyclopedia; typographical clues.)
The User children continue to use the library's dictionary and thesaurus to unravel the document's true meaning. As the Wipers tighten their hold on the User base and food supplies run out, Tesla reads the third volume of "The History of Wipers" to see if she can find anything that could help them. (Lesson: Dictionary; Thesaurus.)
Using more-specialized references to further decipher the document, the User children begin to understand its clues but many of those answers invite more questions. (Lesson: Special subject reference sources.)
The User children and Ms. Bookhart continue to guide Colonel Holon to their location using maps and in doing so Abakas discovers maps to the local sewer systems. In a desperate attempt to get into the User base and retrieve the third Wiper volume, Abakas plans to use the sewers to get past the Wiper barrier. (Lesson: Maps; atlases; world almanac.)
After escaping a patrol, a reunited Abakas and Colonel Holon make their way to the library, hoping to use the third Wiper volume and ruby talisman provided by Tesla to create a defense against the Wipers. (Lesson: Skimming; scanning; paraphrasing; taking notes)
When the User children, Colonel Holon, and Ms. Bookhart determine that the mythical centaur may hold the key to repelling the Wipers they begin devising a plan using that knowledge. Humbuckler's increasing exasperation at his failure to capture the Users may push the base holdouts beyond their limits. (Lesson: Reader's Guide; Children's Magazine Guide)
The User children, Colonel Holon, and Ms. Bookhart prepare two plans: the hologram they intend to display against a cloud to scare the Wipers from Earth, and a record of their research in case their first plan fails. Meanwhile, Humbuckler personally leads the planned Wiper attack on the User base. (Lesson: Audiovisual resources)
When the projections successfully scare the Wipers away and the User base is freed, the Users and Ms. Bookhart celebrate their freedom with a trip back to the library that provided the help needed for their victory. (Lesson: Summarizing reports; concluding research; bibliographic sources)