Andrew Manson is just beginning his career as a doctor at 24 years old, and he has chosen his first position in a small miserable mining town in Wales. Very soon after starting his job, he notices that his patients all seem to have a persistent cough, which was being treated with a 'pink medicine' by the previous doctor. Dr Manson knows that their is something amiss, and sets out to research what is causing the illness amongst the men.