Cardboard Gangsters follows the story of a group of young lads in Darndale, led by Jay Connolly (John Connors), who sell drugs to make a living. They set out in a bid to gain more money and power and enter the big leagues of the drug trade. Things begin to unravel quickly as not everyone in Darndale is willing to let these Cardboard Gangsters achieve the notoriety they crave without a fight.

Film archivist David (Rupert Evans) has been having a rough time lately, as he suspects that his wife Alice (Hannah Hoekstra) has been cheating on him with Alex (Carl Shaaban), one of her work clients. This stress is compounded when David's work partner Claire (Antonia Campbell-Hughes) gives him a reel of to-be-archived footage that shows that his house was the setting for a brutal murder in 1902. Becoming progressively more unsettled and unhinged, David begins to believe that a spectral presence is in his house and ends up following his wife to a nearby canal, where he discovers that she is indeed having an affair with Alex. When Alice goes missing shortly afterwards, David contacts the police- only to become the prime suspect in her disappearance. As the police grow more convinced that David has murdered his wife, he struggles to find proof of his growing suspicion that something otherworldly was instead responsible.