DCI Barnaby and DS Jones investigate the murder of amateur astronomer Jeremy Harper, who was struck on the head with a piece of meteorite on an outing on Moonstone Ridge with the Midsomer Stanton Astronomical Society to observe a total eclipse of the sun.

Harriet Farmer wakes up after having been in a coma since the night she tried to elope, and her boyfriend Finn Robson has been missing since the couple tried to run away together a year before. But when a killer starts targeting members of a chess club shortly after Harriet wakes up, DCI Barnaby begins to wonder if the two cases are connected.