There is good reason for Sir Douglas Wonderly to summon the family and a lawyer to his stately home. He wants to announce a change in his will. At the same time, a dangerous mental patient escapes from a nearby psychiatric ward. Higgins and Lane are put on his trail. But the arrest of the psychopath proves to be extremely difficult. Shortly thereafter, a mysterious hooded man is on the loose in the castle. He frightens Sir Wonderly so much that the old man suffers a shock and falls into a coma. But that's not all: the will suddenly disappears and two sons are murdered. Sir John personally intervenes to solve the case with Higgins and Lane.