Joan Cusack

Joan Cusack will guest-star on Law & Order: SVU, TVGuide.com has learned exclusively.

The 47-year-old Oscar-nominated actress will play the mother of a girl who disappeared some years earlier. When her other daughter also goes missing, she becomes the focus of an investigation.

Cusack's appearance coincides with the introduction of Erik Weber (Henry Ian Cusick),a graphic designer who woos Detective Olivia Benson.

Get the scoop on Benson's new SVU love interest

(No word yet on whether Cusack's character wears a back brace or dances in her underwear — or whether Cusack and Cusick will play music at CUSEC, the Central U.S. Earthquake Consortium.)

The episode will air in the fall.