Based on a short story by American writer George Saunders, the film is set in a luxurious hi-tech prison where inmates are used as guinea pigs for the testing of mind-altering drugs.

Teller’s lag Jeff is on friendly terms with slimy warden Dr Steve Abnesti (Chris Hemsworth) whose doses induce feelings of sadness, love, paranoia or sexual excitement.

But then Jeff falls for fellow prisoner Lizzy (Jurnee Smollett) during his free time which is not part of Abnesti’s plans.

Their relationship leads to a new experiment and the revelation of Abnesti’s dark intentions.

The film boasts a thumping soundtrack and occasional tense moments.

But, after being stretched to fill a feature length format, the plot holes in this simple tale become very apparent.