The annual Chelsea Flower Show is one of the tourist highlights of London. But this year, the event is tainted by the murder of an American tourist in a random act of violence. But when DCI David Brock's Serious Crime division of Scotland Yard investigates, they quickly discover that the killer somehow avoided having both his face and his escape captured on any of the many closed circuit cameras in the area. The conclusion is inescapable - what seemed a senseless, but random, event was in fact a carefully planned murder. But how could the victim- a retired widow traveling with a long time family friend - be worth the trouble and expense of such an elaborate killing? When a very wealthy Russian oligarch is killed in the garden of his palatial estate not far from the hotel where the murdered tourist was staying, Brock and Kolla suspect that something more complicated is going on and that the two killings are somehow related. In a case that takes Brock and his team all the way to the States and back, secrets from a long forgotten past are the key to a string of bloody murders that are just beginning.