CLASSICS: Margaret betrays lazy husband for brother but later comes to know he is a savior. [s]

[Shivangi]

Based during tensions between England and France. There is a unknown man who saves innocent people from the guillotine. A woman named Margaret is married to a very rich but lazy man. Her brother is part of the revolution and is arrested. In order to save her brother she gives some information which could help to nab the vigilante who later she comes to know is none other than her husband pretending to be lazy.
Help me with the name of this book..it's a classic

[Isabel (kittiwake)]

The Scarlet Pimpernel. The wife is called Marguerite rather than Margaret but I'm sure this is the book you are thinking of.

[Shivangi]

OMG yes it is!! Thaaaaankuuu!!