When Hugh finds a scribbled note in Toby's oesophagus during post-mortem, he contacts controversial DCI Thirsk and refers the untimely death to the coroner. In a neighbouring hospital, a ninety year old woman dies, and with a million pound inheritance going solely to one son, the other son suspects foul play and demands a post-mortem. A pulmonary embolism is the cause of death, which is inconsistent with her lifestyle, and the case is also referred to the coroner. Meanwhile, rumours are abound that two nurses are mistreating their patients, and another unexplained death heightens Thirsk's suspicions, but Superintendent Fitzpatrick, whose friend is high on the hospital board, refuses to allow an investigation, trusting the hospital to do an internal inquiry. It's only when Hugh arranges for a nurse friend, Angela, to work as a stooge alongside the rogue nurses that the sickening and sinister truth begins to emerge...