A summer of endless rain in the Peak District leaves the officers of Derbyshire's CID with a problem. They have discovered a man's body lying in shallow water, but torrential rain has swollen the rivers and flooded the roads, making travel difficult and forensic examination impossible. And that's not all. The absence of DS Ben Cooper, on extended leave after an arson attack, has left a serious gap. DS Diane Fry is a reluctant temporary replacement, but now their makeshift team is about to be tested to the limit.