Gaslight focuses on a seemingly normal couple, the Manninghams. It turns out that the suave Jack Manningham is slowly torturing his wife, Bella, into insanity under the guise of kindness. Soon, Bella is visited by a Scotland Yard inspector, Roughy. He convinces her that her husband is a maniacal criminal wanted for a murder committed 15-years-ago. Bella gains confidence in herslf as she and the inspector work together to build up evidence against Jack.