Every season of Dexter has been about its titular serial killer trying really hard to keep his secret. This year, however, it's his sister Deb who has a secret: Not only does she love her brother, but she's in love with him. (As she said, he's the serial more

Following events on " Chemistry ," Dexter is officially sleeping with the enemy. Deb's enemy, at least. How will he react to his sister's missive on tonight's new episode? Look for Dexter's attempt to keep his relationship with Hanna a secret to be more