A new “Luther” trailer shows fan-favorite characters along with a few new faces. The BBC America drama, which follows Idris Elba as the brilliant Detective Chief Inspector John Luther, returns for the first time since 2013. In Season 4, characters will be introduced, including Detective Sergeant Emma Jones. “Game of Thrones” star Rose Leslie plays the character, and she’s featured heavily in the trailer.

The trailer starts with the aftermath of an explosion. It looks like a criminal is terrorizing London, and Jones isn’t sure how to handle it. “What do we do with something like this?” she asks.

The answer, of course, is to bring in Luther. Watch the “Luther” Season 4 trailer below:

Jones doesn’t quite trust Luther. “She is a new member of that policing world, whereby she has now entered into John Luther’s office,” Leslie told Screen Rant in October. “And, you know, she has to then basically work alongside him, having never really -- she’s never really too sure -- she’s dubious of his character. She’s certainly heard of things about this infamous Luther, but she kind of figures him out for herself throughout the two episodes.”

In the trailer, her newness certainly shows. Her character looks frightened in several shots. However, she’ll have to get over her fears and work with a man she doesn’t trust in order to protect London from a vicious felon. BBC America’s synopsis reveals that it’s a “cannibalistic serial killer” who pulls Luther back into crime fighting.

Leslie, who recently returned to “Downton Abbey,” will only appear in two episodes because that’s all “Luther” Season 4 will be. The drama typically had short seasons, with the second and third being four episodes each, but this is shorter than ever. It’s probably due to Elba’s busy schedule. With roles in major movies like this summer’s “Avengers: Age of Ultron” and 2016’s “Star Trek Beyond,” it’s likely hard to schedule a longer season.

“Luther” Season 4 airs Thursday, Dec. 17, at 9 p.m. EST on BBC America.