The Invisible CircleSeven people receive invitations to a 'singular experience' during a weekend in Cornwall in a castle reputedly built on the site of King Arthur's, and situated on an island tenuously connected to the mainland. The sinister host announces that a murder will be committed that night, shows them a sword embedded in a stone (which none of them is able to pull out) and a golden chalice which he claims is the Holy Grail sought by the...