MP John Chilcote is addicted to drugs, which has made his already-unpleasant personality even worse. When he lets down his party in Parliament by botching an important speech, he walks out into a London fog and bumps into his identical cousin, John Loder. When life--including a clinging mistress, a discarded wife, his demanding party bosses, and his responsibilities as a gentleman--close in on him he chucks it all and finds his cousin in order to hide out in a drunken stupor. When his faithful servant follows him, the servant hits on the idea of Loder impersonating Chilcote until he can get his act together. Loder does, and gets emotionally entangled with Mrs. Chilcote and the mistress.