As soon as Adam Kay set foot on a hospital ward for the first time, he realized there's quite a lot they don't teach you at medical school . . . His diaries from the NHS front line - scribbled in secret after long nights, endless days and missed weekends - are hilarious, horrifying and heartbreaking by turns. This is going to hurt is everything you wanted to know about being a junior doctor, and more than a few things you really didn't. And yes, it may leave a scar.