Having earned a promotion to series regular before ever appearing on the show, Rachel Nichols makes her controversial debut on this week's episode of Criminal Minds.

Hotch brings in her character, FBI cadet Ashley Seaver, to assist Reid, Prentiss, Rossi and Morgan as they search for a murderer inside a gated New Mexico community.

The reason Hotch seeks out Seaver in particular? Her past. The youngster's background and experience become clear after a surprising revelation, as revealed below.

Check out the first promo for "What Happens at Home" now ...

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