The Girl in a Mask — Helen K. Maxwell

Caught in a ruthless power struggle at Modern Design magazine, young Dora Fenton confronts a perilous opportunity, yet an oddly attractive one, when she is asked to pose as another man's fiancée. She knows it is a chance to realize her dreams. But what help could she be to William Arkwright, the charming, confident editor-in-chief, a man clearly accustomed to success?
Dora realizes the extent of her dangerous masquerade when she finds herself battling two dangerous opponents-a flamboyant, arrogant woman and an unscrupulous, power-hungry man-and discovers that her description now threatens her own life and the man she has come to love.