AceShowbiz -

Summer never passes without any incident on "Teen Wolf". After spending the past few months in peaceful state, new threat is coming as Scott and his friends are facing graduation in their senior year. "At some point, the scale has to tip one way or the other, which means that things are going to get really good again ... or really bad," Scott says in a preview for the upcoming season 5.

Cody Christian's Theo surprises Scott with his return and the arrival of new villains is going to bring big problems for these teens. Theo is described as "a lone wolf who is drawn to the spooky California town in search of a pack. He's described as athletic and charming yet covert, and while it may appear that the young adult is new to town, his past might suggest otherwise."

The doctor-type villains, meanwhile, apparently will affect someone's mental state. They "use a combination of science and the supernatural for a malevolent and mysterious purpose that will eventually pit Scott and his friends against their greatest enemy yet."

As if it isn't hard enough, Scott and Stiles's friendship is going to be tested. "Why can't you trust anyone?" Scott asks his BFF, who replies, "Because you trust everyone!" Scott also says, "Something's changed. I think it's because of me, and I don't know how to fix it."

"Teen Wolf" returns with a two-part premiere Monday, June 29 at 10 P.M. and Tuesday, June 30 at 9 P.M. on MTV.