Meet our hero… Gareth St. Clair is in a tough spot. His father, who loathes him, is determined to squander the St. Clair fortune and leave him with nothing. Gareth's only inheritance is an old family diary, which may contain secrets from his past… but also the key to his future. The problem is that the diary is written in Italian, and Gareth doesn't know a single Italian word.

Meet our heroine… High society agrees: there is no one like Hyacinth Bridgerton. She is friendly and clever, wickedly honest, and, according to Gareth, you can tolerate her, but only in small doses. Yet something about her –something both charming and irritating– captivates him…

Meet the unfortunate Mozart… Or rather, you can't meet him. But rest assured he’s spinning in his grave every time Gareth and Hyacinth meet at the annual –and decidedly off-key– Smithy-Smith music night. For Hyacinth, every word from Gareth seems like a challenge, so she offers to translate his diary, even though her Italian is far from perfect.

As they delve into the mysterious text, they discover that the answers they seek are not in the diary but between them… and that there is nothing simpler –or perhaps more complex– than a single, perfect kiss.