Though cousins, Sally Browning and Philippa Frome are identical, in looks but not in character. When the spoilt Philippa persuades her identical "twin" to pretend to be Mrs Frome so Philippa can run off on holiday with her secret lover, Sally can only reluctantly agree. An so she embarks upon a new life of wealth and luxury fooling all and sundry-even Philippa's invalid husband Martin. Soon accustomed to her new role and to the deceptions he is loath to make, Sally finds she has more devotion and love to give-especially to the ailing Martin than she had dared to imagine in her wildest dreams.