THE FOURTH ALIEN ARRIVES IN ROSWELL - The mysterious fourth alien is revealed to be a shape-shifter watching over Max (Jason Behr), Isabel (Katherine Heigl) and Michael (Brendan Fehr) after Michael's home situation reaches a crisis point, resulting in a violent confrontation with his foster father Hank (guest star Robert F. Lyons). Max and Isabel's efforts to include Michael in their family only make him feel more isolated, until unexpected help from Philip Evans (Garrett M. Brown) allows Michael to take his life in a new direction. Meanwhile, Sheriff Valenti's flirtation with Amy DeLuca (guest star Diane Farr) heats up, much to the disgust of Maria (Majandra Delfino) and Liz (Shiri Appleby). Paul Shapiro directed the episode written by Toni Grapia