A Gentleman of Dubious Reputation — Grace Burrowes

A matter of matrimony...
Lord Julian Caldicott is summoned to the family seat by his ducal brother, whose bachelorhood is imperiled by the very determined Lady Clarissa Valmond. As the only titled Eligible the hostesses avoid including on their guest lists, Julian has little sympathy for the duke's situation. He nonetheless agrees to lend a hand, because Clarissa is the last person who should be wearing the Caldicott family tiara.

And mayhem!

Matters take a nasty turn when Clarissa's brother, a talented artist, goes missing shortly before his debut London exhibition. Julian must unravel conflicting motives, dishonest witnesses, confusing evidence, old lies, and the real threats facing the duke if he's to find the errant viscount before a fate worse than ruin befalls both surviving Caldicott brothers.