Oxford, 1278 -- the Doctor is keen to put a stop to the pioneering scientific experiments of Roger Bacon. Bacon has developed ideas for submarines, explosives, telescopes and aeroplanes -- history will be cast into chaos if any of these ideas see the light of day.Bacon is living among Franciscan friars who consider him to be a heretic embarrassment. When a friar is found dead in suspicious circumstances, they are keen to implicate Bacon and have him locked away for good.However, more and more murders are being committed and it's increasingly obvious that Bacon cannot be held responsible for them all.