A Librarian from the past teams up with the Librarians of the present to take down an ancient and powerful enemy let loose in the modern day. When superfan Flynn is met with the prospect of teaming with his Librarian hero Darrington Dare, he could not be more excited, until Darrington leaves the Librarians with this dire warning: There can be only one Librarian - ignore at your own peril.

When Baird goes after Nicole Noone in an attempt to repair her rift with the Library, she ends up joining Nicole in a mission to retrieve a dangerous artifact before it falls into the hands of Russian grave robbers. But can she convince Nicole to forgive the Library and return home with her? Or, will Nicole open Baird's eyes to the dangers of a Guardian dedicating herself, heart and soul, to the Library?

Scientists discover new clues as to the catastrophe that ended the reign of the dinosaurs on Earth.

Lagertha is betrayed, and Bjorn must find a way to support the distraught queen; Floki and his settlers arrive in a new land, but it is far from what they expected.

Sax and Happy follow their fortunes to Chinatown. Blue's sister shows up seeking revenge for the murder of her sons. Merry's search draws her ever closer to Very Bad Santa.

A pagan helps Landry search his past. Gawain conducts a murder investigation. Princess Isabella is betrayed.

Kimmy snags Steph for some "soul sister" bonding while DJ attempts a day off. Max breaks a Tanner family heirloom and tries to hide the evidence.

A monumental loss carries a warning from beyond the grave as Gunmar marches for Heartstone Trollmarket. Can the team pull together to save the day?

Marisol tries to drive Marga and Pablo apart. Carlota becomes suspicious of Sara. Lidia notices a crucial difference between Carlos and Francisco.

Tanis recruits the Hicks, who recruit the Hockey Players, to help with a feud on the Rez.

The investigation steps up when Winnie is sent a live rat in a box, with a set of co-ordinates leading to the Pied Piper's latest victim.