[sufue]

Georgette Heyer's Regency Buck is $1.99 right now in the US. Love pretty much everything she wrote. Oh, and it's discountable at Kobo...

Kindle US: https://www.amazon.com/dp/B001P5043C
Kobo US: https://www.kobo.com/us/en/ebook/regency-buck-1

Spoiler:

An altogether unsatisfactory arrangement

After their father's death, Miss Judith Taverner and her brother Peregrine travel to London to meet their guardian, Lord Worth, expecting an elderly gentleman. To their surprise and utter disgust, their guardian is not much older than they are, doesn't want the office of guardian any more than they want him, and is determined to thwart all their interests and return them to the country.

With altogether too many complications

But when Miss Taverner and Peregrine begin to move in the highest social circles, Lord Worth cannot help but entangle himself with his adventuresome wards...