Callie Thorne -- aka Rescue Me nutcase Sheila -- is joining Prison Break for a multi-episode arc, sources confirm. She'll play Pam, the estranged wife of William Fichtner's Mahone -- a role I first told you about in Ask Ausiello. Per my Prison mole, the character will be introduced in Episode 9 when Michael meets up with Pam in an attempt to uncover some dirt on his mad pursuer. (Hint: He finds some.) And in what marks a bit of a breakthrough for Thorne, Pam is not cuckoo for Cocoa Puffs. That's right, Thorne is playing a character who's not crazy. Stop the presses! In other casting news, I'm told Krista Allen is joining ABC's retooled What About Brian for at least six episodes.