With Scotland's prisoner numbers approaching a record high, Lucy Adams investigates the impact of overcrowding, drugs and suicides on inmates and staff, and asks whether our crumbling prison estate can cope much longer. She meets families grieving the loss of their loved ones on the inside, and sheds new light on one of Scotland's most high-profile deaths in custody. Amidst a rising tide of violence and the influence of organised crime, she goes inside one of our largest prisons to witness first-hand a system on the brink.