Paul Conway自己设计制造了一架会思考的机器人,起名“哔哔”(BB)。哔哔善解人意讨人喜欢。万圣节晚上,Paul、Tom、Samantha及哔哔想利用遇节无禁忌的机会,闯入老处女Elvira Parker小姐的前院,没想到她不通情理朝哔哔开枪,打得粉碎,只剩下电脑晶片无损。不久感恩节来临,Paul邀Samantha共进晚餐,Samantha因此被继父打落楼梯,脑部严重撞伤送医诊断,因脑死而回天乏术。Paul得Tom相助,于Samantha脑中植入哔哔电脑微晶片,Samantha因而复活,然而完全为哔哔之思考模式,哔哔怨恨Samantha的继父和Elvira Parker小姐,展开复仇……
Big Baby tells the story of Adam Lewis, a successful horror screenwriter struggling for inspiration for his latest script. After a graphic and realistic nightmare of a hulking man dressed in a baby mask and onesie who axe murders his girlfriend Kate in the middle of the night, Adam gets the inspiration he needs for his new screenplay. Excited about the direction his story is taking, he starts losing himself in his script. Things are better than ever for Adam and Kate until “Big Baby” starts appearing in real life and tormenting and killing victims fueled by his own revenge. Characters from Adam’s script begin to pay him visits pleading for their lives, and he quickly realizes he holds their fate in his hands. Power and fear completely consume Adam until his girlfriend Kate is terrified of the man she once loved.