One Magic Night by Alexa Aston

A man branded a scoundrel by the ton, his family the scandalous Sinning Flynns . . .
A woman burdened with the reputation of her own promiscuous family . . .
Fate brings them together on one magical night . . .

Though he physically resembles his older brothers, Aiden Flynn is not close to being a rogue, though Polite Society lumps him in with the other Sinning Flynns, one of England’s most notorious families. He is more like his maternal grandfather, the Duke of Savernake, the man Aiden models himself after.
Lady Larissa Warren, the product of her mother’s long-ago affair with Viscount Silverton, has yet to find a suitor, thanks to her amoral family’s behavior. Her legal father, Lord Campton, has issued Larissa an ultimatum—find a husband at the annual Savernake Stag Ball—or he will see her married to the ancient Lord Langdon.
A chance meeting brings Aiden and Larissa together just as Aiden learns from his dying grandfather that he will inherit Larkhaven from the duke—if Aiden finds a bride at tonight’s Stag Ball—and weds her before the duke’s impending death.
Aiden decides Larissa is the one for him, but she is determined never to wed a man who would be unfaithful to her, especially one of the infamous Sinning Flynns. Will Aiden convince Larissa he is nothing like his rakehell brothers and win the auburn-haired beauty’s hand?