Eric (Corin Redgrave) is a novelist whose imagination is unusually powerful. While exploring a run-down mansion in the French countryside, looking for sites for his stories, he meets a girl dressed in clothes from another time. Returning to the site, he encounters a modern woman who says he probably met a ghost. He is fascinated by the situation which cannot be what it seems.
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.