The Mad Marquis — Judith Stanton

Unconventional horsewoman Lady Julia Westfall is forced to marry Harry Pelham, Marquis of Rayne, her fiercest rival on race track, to save her beloved horses. Her secret love since girlhood, he is still her secret dream. But what the widowed Marquis proposes is a nightmare -- a loveless marriage with no children. A woman who races her own stallions for the challenge and the thrill can hardly be expected to rein in her passion.

Her new husband sees his dotty Aunt Augusta, loopy Uncle Bertie and lonely daughter Isabeau (who goes everywhere with her imaginary friend) as proof that madness runs in his family, proof that siring more children would bring destruction to the estate. Behind his back, Aunt Augusta helps Julia plot his seduction, Uncle Bertie teaches her to dance for the annual fall ball, and Julia goes against Harry's orders to help his lonely daughter come out of her shell and learn to ride.

When he still spurns Julia's advances, she challenges him to a match race -- her on her best mare against with him on his best stallion. If he wins she'll stop trying to seduce him, but if she wins, he'll let her have her way. But the race is sabotaged, and Isabeau goes missing. Only Julia may know how to save her, and truly win her husband's love.