With the film due out in less than a year, The Maze Runner sequel The Scorch Trials has just cast an important villain.

Aidan Gillen will play Assistant Director Janson also known as Rat-Man in the book to film adaptation of James Dashner’s The Scorch Trials, according to THR.

In Dashner’s book, Janson first appears in The Scorch Trials when the Gladers come across him in the place they’re staying and explains the trials to the main characters. He has a larger role in the third novel, The Death Cure.

Following the big box office return last weekend, 20th Century Fox announced that the Maze Runner sequel will be hitting theaters September 18, 2015 – exactly a year after the first movie opened.

Related: Five Maze Runner book-to-film changes we loved

Pre-production on The Scorch Trials is currently underway in New Mexico. Wes Ball is returning for the sequel.

The Maze Runner has made an impressive $102.2 million worldwide since its September 19 opening, signaling that this series is on track to become a successful YA film series.

Game of Thrones fans will recognize Gillen as the actor who plays Littlefinger (the picture above depicts the actor in his HBO role).