The BAU bid farewell to one of its own on last week's Criminal Minds, but it's welcoming back another this week: Prentiss.

Paget Brewster returns on Wednesday's episode (9/8c, CBS), when Prentiss calls on her BAU pals to help nab an international copycat serial killer who has eluded her at Interpol. After meticulously analyzing his moves and patterns, she believes said unsub will strike next in America.

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"She asks if they would help her and obviously they immediately say yes. ... It's a little reverse of '200,'" showrunner and executive producer Erica Messer tells TVGuide.com, referring to Brewster's previous return, when the BAU asked Prentiss for help after JJ (A.J. Cook) was kidnapped in Season 9. "But the meaning is the same: They are there for each other."

As Messer previously told TVGuide.com, she originally wanted Brewster to come back for the Season 11 premiere, but the actress wasn't available until Grandfathered wrapped for the season in February. That turned out to be a blessing in disguise, as the show was plotting out Morgan's (Shemar Moore) exit, which was always slated for Episode 18. "Having Paget back is always fun — she's the best — but having her back for [Episode] 19 was particularly special because Prentiss knows what it's like from both sides of [watching] someone leaving the team and walking away herself," Messer says. "Everyone misses Morgan and she helps them cope. She has that perspective. And at the same time, it's a happy reunion with her — with us. We're all thrilled whenever she can come back."

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Messer points to some "can't-miss" moments between Prentiss and the team that should please longtime fans, in addition to the fresh dynamic of Prentiss and Tara (Aisha Tyler) interacting for the first time — which will be not unlike Prentiss meeting Blake (Jeanne Tripplehorn) in Season 9. "We made sure they had a moment," she says of writing Tyler, a recurring guest star, into the episode. "I think little things like that are important ... old friends reuniting and new friends meeting."

While the timing of Brewster's guest spot fits in perfectly story-wise, the one bittersweet downside is that there's no reunion between Vonnegut lovers Prentiss and Morgan. "Paget said it was weird not to have Shemar around, and it is. It's still weird," Messer says. But baby girls in mourning can look to Brewster's multiple visits for hope that Moore will drop by at some point (he's certainly open to it).

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"We like to leave that door open for people to come back and play," Messer says. "Not all the time, of course, but when it's right and [schedules] work out. ... Maybe, if everything comes together, they can both come back at the same time one day."

Watch an exclusive sneak peek of Brewster's episode — and see how rough Morgan's absence is on Reid (Matthew Gray Gubler) — below. Criminal Minds airs Wednesdays at 9/8c on CBS.

(Full disclosure: TVGuide.com is owned by CBS.)