Jennifer Carpenter

"Oh, it's been an 11," Jennifer Carpenter says, when asked how intense the last year has been, on a 1 to 10 scale, for her and husband and Dexter co-star Michael C. Hall.

Just working on a show like Dexter would be extreme enough. Season 4 — available as a complete set on Blu-ray and DVD August 17 — ended with Dexter (Hall) finding his wife, Rita (Julie Benz), lying dead in a bathtub, thanks to the killer known as Trinity. Dexter's foster sister, Debra (Carpenter), was dealing with the murder of her on-again-off-again boyfriend, Frank Lundy (Keith Carradine). All this after years of Dexter's murderous scalpeling, mini-sawing and hypodermic needling. "I honestly don't know how these characters experience what they experience without ending up in mental institutions," Carpenter says.

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Then there was the real-life drama. Last winter, a year after Carpenter and Hall were married in a secret New Year's Eve ceremony in Big Sur, California, Hall confirmed he was undergoing treatment for Hodgkin's lymphoma. To hide his hair loss during treatment, Hall wore a knit hat at the Golden Globe and Screen Actors Guild Awards last year, where he won best actor in a drama. His cancer is now in remission and the couple is feeling better than ever, Carpenter says. "To have life come at you in such a big way, from the second Michael was diagnosed until we finally heard the doctors say he's going to be okay, was beyond anything I've ever experienced," she says. "But it became an opportunity to grow and really appreciate each other. In a strange way, his illness was the best thing that ever happened to us." Carpenter chokes up but then laughs. "And Michael's hair is more gorgeous now than it's ever been."

Season 5 premieres Sept. 26 on Showtime and Carpenter says, "it will be fast and furious from the get-go." The premiere opens with "Dexter on his knees, facing the guilt of Rita's murder and saying, 'It was my fault,'" Carpenter says. Debra sees his emotion as an invitation to closeness. "She thinks she'll get the relationship with her brother she always wanted and that they can somehow start anew. But Dexter is typical Dexter and that's not exactly what happens."

Guest stars this season include Julia Stiles as an emotionally needy woman in Dexter's life ("He doesn't know what to do with her," Carpenter says), Jonny Lee Miller and Peter Weller. "This season is really about Dexter finding atonement for the things he's done," she says. Behind the scenes? "It's all about just being grateful."

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