Half of the team becomes trapped on a runaway ghost train, and the rest of the team must help solve the unresolved business of the ghosts on board.

The Librarians head to Paris after a string of robberies leaves mysteriously lovestruck victims in their wake.

The team goes to a college campus with a world-class observatory to discover who is using the Crystal of Dr. John Dee to steal people's memories, in order to own the future.

When the magic door reroutes Charlie, Lysa and Connor to a bizarre manor where a series of Agatha Christie-style murders take place, they must figure out whodunnit, while Vikram tries to track them down with the help of a mysterious tarot card reader.

Connor is forced to reconnect with people from his pre-Library life, and must defeat an old adversary who has grown powerful in his absence.

After a wild bachelorette party with Lysa's childhood best friend, the team wakes up in rough shape and hungover, with no idea how they ended up where they are.

While on a visit to a small-town festival, Connor encounters the very first vampire, and finds himself fighting the clock to save himself from turning into one.

When Vikram attempts to return to 1847 (via a homemade time machine), he inadvertently travels the entire team back to the days of King Arthur, where they learn the truth about a Knight of the Round Table, Camelot, and ... Elaine.

When graffiti starts coming to life and threatening a teenage girl, the team have to work out how these strange events are related to Gregor's Hammer -- and the imminent return of Gregor himself.

General Gregor retrieves the Sword of Mars and uses it to take over the country of Caucasylvia (remember from the Train episode), gaining control of their nuclear arsenal. The team must steal the Sword to prevent world calamity.