Lee Kingley (Lennie James) has been sentenced to ten years for a firearms offence and grievous bodily harm. The truth is, he was protecting a member of his family from a violent criminal. When his appeal is turned down, he manifests his anger by getting ejected from the drugs-free unit and transferred to the main prison, HMP Mandrake. The prison staff and his fellow inmates prove a different battleground as Lee continues to fight to prove his innocence. Uncompromising and grim, this award-winning drama compellingly presents the brutal reality of the British prison system. From friendship, jealousy, threats and stabbings to sexual assault and suicide, all prison life is here, at its most extreme.