When cool-headed Phyllida visits the World's End Investigation Bureau to offer a curious case concerning her fiance, proprietor Lily Raynor is intrigued - and privately excited. For accepting the case means taking an unexpected trip abroad, to France. Phyllida's fiance, Wilberforce, is currently in an asylum in Brittany, after a tragic incident which resulted in the death of his father. Did he kill him on purpose - or was it an accident? Wilberforce's innocence looks increasingly in doubt when another murder happens at the asylum - and the evidence points to Wilberforce being the culprit. Phyllida fears for Wilberforce's wellbeing, but she can't marry a murderer! With the engagement hanging in the balance, Phyllida wants to know the truth before it's too late. Lily and her assistant, Felix Wilbraham, journey to rural France to uncover the truth, but the case takes an unexpected turn when they discover that the accused man has escaped the asylum and is nowhere to be found. Soon the intrepid investigators are in over their heads with much greater and unexpected powers at play . . .