The counterfeit guest

"It is 1797, and Mary Finch, heroine of The Blacksone Key, is now a wealthy heiress. Young ladies in her situation ought to marry well--as her friend Susannah Armitage has. But is Susannah's marriage to Colonel Crosby-Nash all that it seems? Mary thinks not, and when her suspicions lead to a meeting with the elusive spymaster Cuthbert Shy, he reveals the terrible truth: the colonel is a traitor. At Shy's request, Mary agrees to accompany the Crosby-Nashes to their country estate in order to discover his communicating with Shy is murderously cut off. If only Mary could contact the redoubtable Captain Robert Holland--but as he has inexplicably ended their friendship, his help seems out of reach..."--p.[4] of cover.