Tim accuses Mark of being the killer, but nobody believes him. Gabi tries to prove that Mark isn't the killer, and she takes another look at the tape of Elizabeth getting murdered, in order to find a proof. When Tim can't find Meg in the house, he goes after her. Casey and Michael find Grogan's boat -- complete with a puddle of Elizabeth's blood. Vanessa falls down into a hole. Mark tells Meg that he's not going to go back to the others until he can prove that he's not the killer. (thetvdb.com)