She's back!

Prentiss (Paget Brewster) returns to Criminal Minds starting in Wednesday's (Oct. 12) episode — and judging by our exclusive first look, her first case is such a doozy that we can't even talk about. Or at least she and Alvez (Adam Rodriguez) can't.

"What happened out there, Prentiss — keep that between us," he ominously says.

Criminal Minds Season 12: Everything you need to know

Prentiss makes the transatlantic trek to help out the BAU while Hotch (Thomas Gibson) is on a special assignment. The case involves the disappearances of three women, whose limbs are found encased in cement. Bonus sneak peek: We were on set to see the creation of one of the arms.

👋 from the #CriminalMinds set

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So what, exactly, happened between Alvez and Prentiss "out there"? Were they attacked by a dozen cement arms? Did the unsub try to dismember them? Or is it something else? Showrunner Erica Messer told us that the two will form a "fun friendship" after an initial awkward meet-cute. There's certainly nothing fun about that exchange though.

Criminal Minds airs Wednesdays at 9/8c on CBS.

(Full disclosure: is owned by CBS.)