The Nanny (2002)

A key part of Kelly's job description as a nanny is to keep little Joey entertained and Joey's favorite game is Damsel-In-Distress where he plays the black-hearted villain who leaves the flame-haired Kelly securely bound and gagged. One day, when Joey goes to his piano lesson, he leaves Kelly still tied and silenced. Joey's mother, Laura, discovers the unfortunate nanny and rather than release her, Laura, teases, tickles and spanks the bound woman. Kelly enjoys her little tie up games with her charge, but Joey keeps forgetting to release his nanny, and since Laura enjoys having a helpless woman to torment, that's just fine with her. That is, until young Joey discovers the two women playing a game of mad scientist.