The Highbinders.

Author David Marshall is sandbagged by holdup men and loses his memory. He finds his way to a bookshop run by his friend Ladd, who takes him in with the hope of helping him to regain his memory. David there meets Hope Masterson and falls in love with her. Bill Dorgan, a gangster in love with Hope, kidnaps her, and David comes to her rescue. David is hit again on the head, and this time he regains his memory. He still recognizes Hope, however, and they look forward to a long and happy life together.