New Year's Eve should be a time for celebrating. But for Detective Superintendent William Lorimer, this is one night he will never forget... Called to a house after gunshots are reported, the carnage Lorimer finds there leaves him traumatised and questioning his future with Police Scotland. Meanwhile, the body count is rising on Glasgow's streets. A number of known addicts are dying from accidental overdoses, but something's not adding up. Where would the city's poorest residents get hold of high-quality morphine? As Lorimer struggles to return to duty, he spots a link between the deaths and a previous case involving the euthanasia of vulnerable patients. It seems the man responsible has resurfaced - and this time he's got the backing of a dangerous criminal from Glasgow's underworld.