Watch the Wall, My Darling — Jane Aiken Hodge

The carriage that was rolling swiftly along the rainy English marsh on the road from London suddenly stopped. A barricade blocked the way. Dark figures surrounded them. Christina had no time to cry out as strong arms caught her from behind. A hand covered her mouth. She bit it as hard as she could.

She looked up at the tall, masked stranger, and a mysterious, frightening sensation swept over her. Those fiery brown eyes gazed at her in a way she had never known before...
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UK CORONET Edition:

ADVENTURE, LOVE, INTRIGUE...

Christina Tretton came home from the wilds of America to the stranger, solitary world of Romney Marsh. There she met her tyrannical grandfather and her two cousins, one of whol he has degreed she must marry. Richard proves to be a selfish fop, Ross overbearing and heartless - and moreover, somehow mixed up with dark deeds on the marsh. Whom can she trust? Where does Ross disappear to, and what is he doing? And why should she obey him when his whims mean danger for herself?