DS Jones goes undercover at the Oblong Foundation after one of the cult's young female members disappears suddenly. But he and DCI Barnaby soon start digging into an old case involving the death of a couple in a boat explosion.

When a missing VAT inspector turns up dead in a vat of cider, DCI Barnaby and DS Jones must hunt for a 'giant' killer within a Midsomer village steeped in bizarre local traditions.