A woman about to begin her maternity leave from work begins to suspect that her replacement is plotting to take over her life.
Ellen gets pregnant after landing a big contract for her firm of architects. She hires Paula as cover but soon fears she's made a terrible mistake.
Ellen tries to juggle her new baby with her return to work and her investigation into Paula. Ellen eventually confronts Paula and forces her to confess what she's been hiding.
Final: Ellen thinks she has proof that Paula is disturbed but no one else sees it her way. After a catastrophic celebration at Ellen's finished building, her family as well as her career face ruin.