Claire Barclay, owner of a mystery book tour company, collects three women at the Manchester airport who have flown in from Tucson, Arizona, then starts on a tour of Yorkshire and the sites of mystery novels. She meets the rest of the tour in York: two British couples and Phillip, a single man. 

Claire has scheduled stops at sites of interest, starting with the York Chocolate Factory. Here, in pursuit of Phillip who will not stick with the tour, she finds the body of a security guard. She cannot see any connection with her tour and leaves York, driving the group up on the moors and stopping at the famous Ralph's Cross where moorland stretches for miles. Here, her American ladies report the sudden death of Phillip in the surrounding bog. 

Detective Inspector Mark Evans, a friend of Phillip's and Claire's significant other, investigates. Mark tells her Phillip worked for Scotland Yard and was on the trail of a drug distribution scheme. Claire is determined her Tucson ladies will not be dragged into the murder inquiry or any other police investigation, but they are determined they will. They are intelligent, expert mystery novel fans, and observant. They precipitate Claire and themselves into a confrontation with the murderer.