While chasing one of the Library's missing artifacts, Flynn is kidnapped by a mysterious stranger with both amnesia and a collection of all the Library's missing artifacts. Soon all of them are in pursuit of the Staff of Zarathustra before it falls into the hands of Prospero.

The Clipping Book sends the team to a high-tech research facility, where the researchers have been turned into mindless monsters by some bizarre power source in the center's lab. When they disconnect the artifact, however, they find themselves stuck in a time loop.

The Librarians' two-front battle comes to a head when the Library is simultaneously infiltrated by DOSA and Apep. Flynn, Baird, Stone, Cassandra, Ezekiel and Jenkins must all put aside their differences in an attempt to save the Library, the world and themselves.

When Santa takes Flynn, Baird and Jenkins on his first vacation in centuries, he leaves his beloved sleigh in the care of the Librarians. But when Ezekiel's career criminal mother steals the magic door, they must use the sleigh to save her, as well as Christmas itself, from Santa's Grinch of a brother, the Patron Saint of Thieves.

When Jenkins body-switches with a 28-year-old slacker named Jeff, he must find his way back into the Library to correct the mistake. But he will need a team to do it, and enlists the help of Jeff’s hapless Dungeons & Dragons friends. Can they make it in time, before Jeff destroys the Library?

After the world is morphed into a horrible and unrecognizable place – one where the Library never existed – it's up to Baird to bring the Librarians together before this bleak, knowledge-less world becomes the new reality.