The Mysterious Marquis — Karen Cogan

When her best friend disappears without a trace, Lady Marianne Bentley is perplexed. Since the girl's parents seem opposed to an all-out investigation, Marianne decides to take matters into her own hands. She soon discovers that a certain Marquis, with whom she has never been cordial, was the last to keep company with her young friend. Marianne's conviction that he is involved in the disappearance leads her to renew their acquaintance in the hope of obtaining a clue. But, she is taken off guard by his wit and charm and seeming sincerity; and soon, she finds herself falling in love with the one man whom she vowed never to trust.