Young prison officer Nicholas Glass is finding the stresses of the job increasingly hard to handle. Bullied and abused by inmates and colleagues alike, every day is getting longer than the one before. When a group of cons use outside help to threaten his wife and daughter, Glass agrees to help them out with a 'favour'. But, as their threats escalate, and one favour leads to another, Glass grows ever closer to breaking point. And when glass breaks, it shatters.