Richard Fountain [Patrick Mower], Oxford University's authority on Greek mythology,is in Greece researching Minoan rites when word comes back that Fountainhas become chummy with people involved in drugs, orgiastic rituals, andpossibly a rash of murders. Since Richard is the son of an English foreignsecretary and the almost-fiancé of Penelope Goodrich [Madeline Hind], daughter ofLancaster College's provost, Walter Goodrich [Peter Cushing], Investigator Tony Seymour [Alex Davion]has been summoned to find Richard and bring him back to England. Tonyleaves immediately for Greece, accompanied by Richard's almost-fiance, hisstudent Bob Kirby [Johnny Sekka], and Major Derek Longboy [Patrick McNee] of the British Attache. Aboutthe only thing that is known about Richard's status is that he leftEngland a virgin and, much to Penelope's dismay, he's taken up with awoman named Chriseis Konstantanini [Imogen Hassal].Tony sends a telegram to Richard's villa in Mykonos, advising him oftheir arrival on Thursday, but Richard apparently does not wish to seethem, as he immediately vacates the premises, sending his 'saviors' on awild goose chase to find him. All they have to go on is a note found inRichard's room, in which he mentions the city of Hydra. They contactColonel Stavros [David Lodge] of Greek Intelligence for help. Stavros places ahelicopter at their disposal, and they fly to Hydra, then take a landrover to the Monastery of the Blood of Christ. There, the abbot admits tohaving recently treated Richard for an ancient sickness having 'to do withthe blood.' Unfortunately, Richard is no longer at the monastery. Thosewho brought him have carried him off again in the direction of a nearbyfort.While they are interviewing the abbot, Penelope begins to feel ill.They write it off as too much wine and sun but decide to leave her behindat the monastery while they follow the mule trail up the mountain to thefort. When they arrive, they find that they have stumbled on thebeginnings of a ritual. Chriseis and her followers escape, taking themules. Richard is there, too, but he is in some sort of trance. Withoutthe mules, the search party is forced to remain the night, intending forDerek to return to the monastery early the next morning and get Penelopeoff the island while Tony and Bob attempt to carry Richard down themountain and back to the monastery.During the night, Richard comes out of the trance. He admits to stillbeing a virgin but explains that Chriseis' influence over him is verystrong. Even now, they must watch out for her, he says, as Chriseis willbe back. The next morning, Richard is still too weak to travel, so theplan changes such that Derek will have to bring in the helicopter in orderto transport Richard. Richard refuses to allow Derek to leave. He requeststhat they first carry him outside. There, he shouts a prayer to the gods,asking for protection for Derek and the others. As a sign, Richard sees aneagle swooping. Based on the number of the swoops, Richard predicts thatone of their party will die before they can get back to Hydra.Derek makes it down the mountain okay and sees Penelope off at thedock. Unfortunately, on the way down he was seen by Chriseis who, seeingDerek leaving, is making her way back to the fort. Derek is not far behindand trying to catch up with her. Chriseis starts a rockslide, which knocksDerek over a cliff. Hanging on for dear life, Derek screams loudly. Tonyand Bob rush to his aid, leaving Richard alone in the fort. Chriseis takesthis moment to slip in and drink Richard's blood. When Tony and Bob senseher presence, Bob goes back to help Richard, while Tony triesunsuccessfully to pull Derek back over the cliff. Bob and Chriseisstruggle, but Chriseis falls down a flight of stairs and appears to bedead. Bob attempts to put a cane through her heart, but Tony stops himbefore it turns from an accident into a murder.Richard, Bob, and Tony return to England, where Richard takes up hisstudies again at Oxford and marries Penelope. But the pressures placed onhim by Provost Goodrich cause Richard to remain impotent and to revivememories of Chriseis. Bob senses that Richard is backsliding and sends forTony's help. Tony arrives on the day of Richard's address at LancasterCollege's quincentenary dinner. After the opening prayers and while thequests dine on the traditional boar's head and peacock with feathers,Richard begins to deliver his welcome-back speech. He winds up causing ariot when he accuses the academic world of 'leeching on' and 'possessing'the minds, souls, and bodies of the academics as well as their students.He points to all the 'smooth deceivers' dressed in their scarlet gowns,and fingers Goodrich as the worst of all.While the academics compose themselves, Richard leads Penelope to hisoffice where he is finally able to experience sexual freedom by rippingoff her bodice and drinking blood from her neck. Tony and Bob breakRichard away from Penelope's neck. Richard attempts to flee over therooftops but goes skittering off, impaling himself on the wrought ironfence below. Provost Goodrich tearfully pronounces their deaths as due to'suicide', but Bob and Tony complete the act by driving stakes throughRichard and Penelope's hearts. [Original Synopsis by bj_kuehl.]