It's been a long three years without our favorite brooding London detective, but the BBC just dropped its first trailer for the highly anticipated return of its award-winning series, Luther. Our hero, DCI John Luther (Idris Elba), seems as on edge and broody as ever, and that can only be good news for diehard fans.

(Some spoilers for first four seasons below.)

Luther has earned critical raves and built up a solid following since it first debuted on BBC One in 2010, and it has been one of the top-rated shows on BBC America, along with Doctor Who and Top Gear. Much of that is due to Elba's powerhouse performance in the title role—easily his best work since he played Stringer Bell on The Wire.

Luther has never shied away from the darkest corners of the human psyche, and the writers are more than willing to bump off major characters unexpectedly. John Luther is obsessively devoted to his work and struggles a bit with anger management. There's more than a little darkness in him; perhaps that's why the crimes he investigates affect him so deeply. His work cost him his marriage and at least one partner, and his ongoing fascination with genius psychopath Alice Morgan (Ruth Wilson) is decidedly unhealthy.

Based on the trailer, we're in for another terrific dark and gritty season. Luther has a new partner in DS Catherine Halliday (Wunmi Mosaku), and the two are hot on the trail of a budding serial killer in a doll-like mask. As Luther says, "It's gonna get worse. Much worse." It always does.

The biggest reveal is the briefest glimpse of Alice, presumed dead under mysterious circumstances since season 4. Their relationship is... complicated. Luther first encountered her in the pilot episode when she was accused of murdering both her parents. He knows she's guilty but is unable to prove it and reluctantly lets her walk.

Alice becomes obsessed with Luther—a man she couldn't fool with her considerable manipulative gifts. Over the course of the series, an uneasy alliance develops, as her intellect and insight into the serial-killer nature prove to be invaluable. Plus, Wilson makes the character so darn charming and likable, nobody is surprised when Luther finally succumbs to her invitation to flee London with her at the end of season 3.

But Luther is once again alone and brooding at the start of season 4, where he spends part of his time back on the force trying in vain to find out what happened to Alice. It looks like we'll finally get some answers—including whether she's back to help Luther or up to her old murderous tricks again. And then there's the ominous voice (over a haunting cover of Britney Spears' "Toxic"): "I always thought she'd be the end of you. And then she'd be the end of us all."

The new four-episode season of Luther will air on BBC One in December and should come to BBC America sometime next year. The sooner, the better!