The Wicked Sister by Mary Lancaster

The debutante meets the radical…

Lady Maria returns to Braithwaite Castle from her first London season with a scandal about to break over her head. A sweet-natured girl, she loathes confrontation and is dreading the scolding from her mother and brother. But help comes from an unexpected source – Lord Braithwaite’s new secretary, Michael Hanson.
Michael is poor, clever, ambitious – and a political radical. Engaged to be married to a lady who actively shares his views, he never imagines he could fall for his employer’s lovely, if rather haunted, sister. But there is more than frivolity to Maria, and he is quickly drawn to her humor and compassion, and to the troubles her good-nature keeps heaping upon her.
When her first love pops back into her life to blackmail her over her indiscretion a year ago, it is Michael she turns to for help. But Michael, too, has his problems as he is under suspicion for publishing seditious pamphlets that could affect Britain’s last battle with Napoleon Bonaparte.
As the European stage is set for Waterloo, Michael and Maria work together to find the conspirators before it is too late.
In the process, they fall in love, but honor as well as their difference in rank, might keep them apart…