'Weeds' Recruits Natasha Lyonne for Hourlong Series Finale (Exclusive)

Natasha Lyonne Headshot - P 2012

Natasha Lyonne Headshot - P 2012

The mystery surrounding the series finale of Showtime's Weeds has been kicked up a notch.

American Pie's Natasha Lyonne has been tapped to guest star in Weeds' hourlong series finale, The Hollywood Reporter has learned exclusively.

STORY: TCA 2012: Jenji Kohan, Mary-Louise Parker Reflect on Final Season of 'Weeds'

Lyonne will play a woman named Tiffani in the episode, with additional details her role being kept under wraps.

Not much is known about the two-part episode, set for Sept. 16, with showrunner Jenji Kohan and the cast telling reporters this week at the Television Critics Association's summer press tour that the series will not end with another cliffhanger.

STORY: 'Weeds' Postmortem: EP Reveals the Back Story Behind Nancy's Shooter

Rather than the Season 7 finale that ended with perhaps the series' biggest cliffhanger yet after Nancy (Mary-Louise Parker) was shot with a quick cut to black, the finale will tie up many loose ends and feature a memory lane of past characters.

"[Kohan] managed to bring things together in a really beautiful way," Parker said this week. "She didn’t make it a happily-ever-after thing, but there was hope, and there was some sort of benediction. I cried when I read it. I think the finale is beautifully written, and I hope it lives up to what she wrote.”

Production on the finale started this week.

STORY: 'Weeds' Creator Jenji Kohan Revisiting 'Little Boxes' as the Showtime Comedy Prepares to Sign Off (Q&A)

Lyonne, repped by APA, 3 Arts Entertainment and Schreck Rose, recently wrapped a starring role in the indie dramedy Clutter with Carol Kane and next will be seen in Michael Urie's directorial debut, He's Way More Famous Than You. Her credits include But I'm a Cheerleader, the American Pie sequels and episodes of New Girl and Law & Order: SVU.

Weeds airs at 10 p.m. Sundays on Showtime.

Email: Lesley.Goldberg@thr.com; Twitter: @Snoodit