A poor schoolmistress no longer, Mary Finch has come into her inheritance at last.  She has been enjoying herself redecorating White Ladies, and has two former colleagues as companions.   Yet she misses the thrill of her Adventure, and the proximity of the man she loves, Captain Robert Holland.  Soon circumstances bring her once again to meet with Holland and to stay with his family, and then at the strange, exotic Champian Hall to act as companion to Holland’s newly married cousin, Susannah.  For Mary is once again working as a spy herself, and it looks as though Susannah’s husband is a traitor.

I confess to finding the first installment of Mary’s adventures, The Blackstone Key,  (also reviewed on this site) enjoyable but somewhat ponderous.  This novel, too, does not exactly race along and flags in places, but I found that it contained more, and thus filled its considerable length better.   To call it a mystery is something of a misnomer, and Mary’s own term "Adventure" suits it better, as we know who is doing what and why, and it is the thrill of the chase that keeps the pages turning, rather than anything unknown.  There is a good feel for the period in here, from Mary’s enjoyment of London life to the true history of the naval mutinies and descriptions of navy life.   Mary makes for an engagingly plucky heroine, and the cloak-and-dagger business of spying is contrasted well against the rather Jane Austen backdrop of everyday life in the 1790s.  This is just the series for anybody wanting something a bit different from both historical whodunits and Regency romances.