Bullard (Barry Jackson) asks Barnaby (Neil Dudgeon) to investigate the disappearance of Lucy Oliver (Elizabeth Crarer), the daughter of some friends. Lucy was a member of the Oblong Foundation, a New Age cult based at Malham Hall. Jones (Jason Hughes) returns from leave, with a beard, and Barnaby seizes the opportunity to send him into the cult, undercover, as new recruit Cosmo Jones.