Agatha is promoting a charity film evening for Sir Charles Fraith, who has made it clear that the Dembley ramblers group are not welcome on his land. When their outspoken leader Jessica Tartinck is murdered, Fraith is the prime suspect, but Agatha discovers that Jessica's campaigning and promiscuity did not make her universally popular. Persuading the reluctant object of her affections, James Lacey, to pose with her as a married couple, Agatha infiltrates the ramblers, who include bereaved boyfriend Jeff and gay couple Alice and Kirsty, as well as Deborah, Fraith's fiancee, to investigate. After surviving a hit and run, Agatha believes she has found the killer, but then realizes they are possibly the least likely of her suspects.