When Dr. Alan Delaney is killed in a hit and run accident, Barnaby realises the real target was Delaney's senior partner, Dr. James Kirkwood. Is the killer trying to prevent James from marrying the beautiful divorcee, Delyth Mostyn? And how is his death linked to £30,000 which is missing from the surgery accounts? Barnaby and Jones must travel to Snowdonia to unravel the truth.