Sony's Screen Gems has acquired the thriller spec Within, written by Jack Olsen, and set to be produced by Unique Features banner.

According to The Hollywood Reporter, the story is in the vein of The Hand That Rocks the Cradle, and revolves around a couple whose marriage is threatened when the baby surrogate they have hired becomes obsessed with wanting the husband and the baby for herself.

Screen Gems president Clint Culpepper and senior vp production Scott Strauss will oversee the project.

No production date has been set.