"The Librarians" is based on the fan-favorite TNT film series starring Noah Wyle and follows librarians Ezekiel, Jacob, and Cassandra, their Guardian Eve Baird, and the Annex's caretaker Jenkins. The film series revolves around Flynn Carsen as he takes up the mantle of librarian, in charge of a library which houses magical and mythological objects. In addition, he's meant to protect the world from those objects and to go up against magical situations. The TV series begins as Flynn dubs three people with the job of Librarian. The team of librarians goes up against a range of mythological, fairy tale, and folklore situations.

The first three seasons have seen the team deal with a range of villains from the Serpent Brotherhood to the literary villains Prospero and Moriarty to Apep from Egyptian mythology. Other episodes have featured vampires, the team turning into fairy tale characters, and Morgan le Fay.

The series stars Rebecca Romijn as Eve, Christian Kane as Jacob, Lindy Booth as Cassandra, John Harlan Kim as Ezekiel, John Larroquette as Jenkins, with Noah Wyle co-starring as Flynn.

Spoilers for the two-hour premiere

The first episode of season 4 is called "And the Dark Secret." In the episode description released by TNT, the episode will find the librarians setting out to find the four cornerstones of The Library of Alexandria after a sect of the Vatican Church discovers a map with the stones' whereabouts.

The description also teases that the stones can be used to destroy The Library, and the team will turn to an unexpected ally.

The second hour will dive into holiday fun when Santa takes Eve, Flynn, and Jenkins along for a vacation. Though when Santa leaves his sleigh in the care of the team, Ezekiel's mother steals the magic door.

To save her the librarians will need to use the sleigh, while also saving Christmas from Santa's brother, the Patron Saint of Thieves. The episode is called "And the Steal of Fortune."

What else to expect in the new season

Other teases for season 4 include a time-traveling librarian, Civil war ghosts attacking a town, what's being described as a "Freaky Friday" situation, and a luck stealing casino.

The trailer for the new season reveals the foreboding news that The Library is "uncoupling from reality," which will lead Flynn and Eve to tieing themselves to The Library which will result in immortality. Though a woman from Flynn's past will show up and has been described as a dirty little secret of The Library. In addition, it has been revealed that Noah Wyle will appear in seven of the twelve episodes. The trailer also shows Flynn and Eve being trapped inside a black and white film, with the team struggling to figure out how to free them.

The new season of "The Librarians" will premiere with two episodes December 13 on TNT.