Based on the incredible true story of the 1983 mass breakout of 38 IRA prisoners from a high-security prison, the film charts how inmate Larry Marley engineered the largest European prison escape since World War II. Up against the most state-of-the-art and secure prison in the whole of Europe (a prison within a prison), Larry must coordinate with inmates across several cellblocks. While scheming his way towards pulling off this feat, Larry forms a close bond with prison warden Gordon Close.