Amanda Seyfried’s attempt to tackle some edgy theatrical material has been thwarted by scheduling issues. EW has learned that the actress, best known for her singing-and-dancing role in Mamma Mia, won’t be starring in Zack Snyder’s 1960s-set, R-rated action fantasy Sucker Punch for Warner Bros. Seyfried was offered the lead role of Baby Doll, a young woman who has been committed to an insane asylum and fantasizes about escaping with the help of her fellow inmates. But with shooting scheduled for the fall, HBO won’t release her from her Big Love commitment, which will be in the middle of filming its fourth season. No word yet on who Snyder will find as her replacement.

Seyfried is scheduled to complete her work on Chloe, in which she costars opposite Liam Neeson and Julianne Moore, this week. It’s unclear whether or not Neeson’s absence will prolong her schedule on the film. With Big Love concluding its third season Sunday night, Seyfried can be seen next in the Diablo Cody-penned horror film Jennifer’s Body, opposite Megan Fox.