4

Debra, Dexter's adoptive sister, is a vice cop desperate to be transferred to Homicide, a goal she accomplishes in the second episode. Deb is smart, but unsure of herself, and so relies on Dexter's "expertise" to solve difficult cases. When one of Dexter's victims is found, Debra formulates a theory that could expose him. Dexter steers the investigation in a different direction, pointing to her lack of experience and knowing all along that her theory is correct.

(wikipedia.org)