Though cousins Sally Browning and Philippa Frome are identical - in looks but not in character. When the married spoilt Philippa persuades her twin to pretend to be Mrs Frome so Philippa can run off on holiday with her secret lover Sally can only reluctantly agree. And 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 Sally finds she has more devotion and love to give to the ailing Martin than she had imagined possible.