Alex Preston is murdered and his corpse placed in the Crowcall stone circle in a field on his land. He was intending to plough the field,setting him at odds with the New Dawn druids,all of whom have alibis. His wife Eleanor was two-timing him with her fencing instructor, and local cop Trevor Gibson destroys her alibi but when Leticia Clifford, a leading druid,is killed in the same way as Alex,crimes of passion are ruled out. As Barnaby and Jones disagree over the possibility of Gibson's involvement Barnaby seeks the advice of local historian Caradoc Singer,hoping to discover if the killings were motivated by greed or bound up with popular superstitions such as the Sleeper Under the Hill.