Clara Angelo does not really love her husband, David, a distinguished Roman banker, who is old, ugly and bent. Unknown to her husband, her mother, Mrs. Brunschaut, has involved her in a foreign conspiracy, in order that she may add to the extravagance of her living. David Angelo becomes aware of the intrigue, but before he can discover just what it is, he is called to Naples on business. He leaves his fortune in care of his partner, Stroggi, to be given to Mrs. Angelo in case anything happens to him. On his trip back home he stops to see Vesuvius, and is caught by a sudden eruption and smothered under the hot ashes. He is, however, rescued, and under the treatment of a great scientist, is restored to health; his physical disabilities have also been removed, and he is straight and rejuvenated in appearance, so much so that the doctor tells him he would not be believed if he declared himself to be David Angelo, and he decides to let the world believe that he is dead. He returns to Rome and startles the national treasurer by his brilliant suggestions in connection with finance, spies on the conspirators who are seeking to compromise his wife, is introduced in his own home without being recognized, and prevents his wife’s fortune being stolen by his former partner. He also wins his wife’s love, and, upon consenting to marry him, she rejoices to learn that he is really the supposedly dead David Angelo.