'Teen Wolf' Season 6 Episode 17 Air Date, Synopsis, Spoilers: Colton Haynes Returns

Scott McCall (Tyler Posey) and his pack are in need of a back-up in "Teen Wolf" Season 6 Episode 17. Good thing one of his friends, Jackson Whittemore, is ready to come back and lend a helping hand. Colton Haynes, formerly from "Arrow" and soon in "American Horror Story: Cult," will appear in next week's episode titled "Werewolves of London."

After six action-packed seasons, MTV's teen paranormal drama has seen some fan-favorites come and go. However, in its final season, these characters have not been around in the past few years are coming back for one final adventure with the wolf pack. 

Carter Matt revealed that Haynes and co-star Charlie Carver (Ethan) will appear in the next episode of "Teen Wolf" Season 6. The site suggested that the title of the episode, "Werewolves of London," could be a reference to where Jackson went after Haynes exited the show years ago. 

Here is the synopsis of "Teen Wolf" Season 6 Episode 17: "The pack reels after a shocking attack; Scott tries to [bring in] reinforcements."

Of course, Haynes is not the only familiar face who made an appearance in the final season of the teen paranormal drama. Dylan O'Brien a.k.a. Stiles Stilinski also returned in the first half of Season 6. 

Meanwhile, the lives of Scott, Malia (Shelley Hennig) and the rest of the pack are still in danger. This Sunday's episode saw Gerard (Michael Hogan) armed his army with a goal to kill every supernatural being in the world. When the two sides unexpectedly clashed, Gerard and his army fired at the pack and, when the gunshots ceased, someone was seen lying on the floor with a pool of blood. 

Who could it be? Find out when "Teen Wolf" Season 6 Episode 17, "Werewolves of London," airs next Sunday, Sept. 10, on MTV.