At a converted movie studio amputee actors help prepare army medics for the shock and gore of combat wounds, while at the base for anti-terror operations in East Africa diarrhoea threatens national security.

Beyond weapons and strategy, this is about the other side of war - how to tackle the challenging adversaries of panic, exhaustion, heat and noise. From maggot debridement therapy to the slightly tricky ethics of testicular transplants, Roach takes us on a rollicking ride full of insights that fascinate as much as they disgust.

Not one to shrink away from the gritty details, she samples caffeinated meat, sniffs archival World War II stink bombs, dodges enemy fire with the Marine Corps' paintball team and stays up all night with the sleep-deprived crew of a nuclear submarine.