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"Dexter" Season 5, Episode 4: "Beauty and the Beast"

Michael C. Hall on Dexter. (Showtime) Showtime

NEW YORK (CBS) On Sunday night's "Dexter," the blood analyst catches the mysterious woman who may have witnessed him in the act of killing a killer.

In an episode called "Beauty and the Beast," Deb calls and asks for Dexter's help on the Santa Muerta case, even though he's on leave.

Dexter goes, with the secret hope that he can possibly ID this mystery woman on the side.

Dexter gets his ID: the woman's name is Lumen Ann Pierce (played by guest star Julia Stiles). He tries to ply her with aspirin or antibiotics (that he stole from Vince's stash) but she refuses then. Meanwhile, he learns that Lumen is a runaway and he picks up the luggage she never received.

What happens to Lumen? Apparently, that is for next week.