Vampire Diaries 4x05 Official Synopsis

Ep5 'The Killer' 

"THE HUNTER'S MARK — Stefan (Paul Wesley) and Klaus (Joseph Morgan) form an uneasy alliance to try and contain the danger that Connor (guest star Todd Williams) has unleashed on the town. When Connor takes Jeremy (Steven R. McQueen), Matt (Zach Roerig) and April (guest star Grace Phipps) hostage at the Grill, Stefan and Damon (Ian Somerhalder) have a serious disagreement about the best course of action, and Elena (Nina Dobrev) is again caught between the two brothers. The situation quickly turns violent when Klaus sends one of his hybrids, Dean (guest star Blake Hood, 'The Young and the Restless') to stand up to Connor. Caroline (Candice Accola) is surprised to find Hayley (guest star Phoebe Tonkin) at the Lockwood mansion. Meanwhile, Professor Shane (guest star David Alpay) works with Bonnie (Kat Graham) to help her get past her fear and guilt."