It's in His Kiss (Bridgertons Book 7)

All the ton agree: there is no one quite like Hyacinth Bridgerton.. Fiendishly smart, devilishly outspoken and – according to some, particularly Gareth St. Clair – probably best in small doses. But there’s something about her – something charming and vexing – that grabs one and won’t quite let go. Gareth and Hyacinth cross paths at the annual – and annually discordant – Smythe-Smith musicale. To Hyacinth, Gareth’s every word seems a dare, and she offers to help him out with a knotty inheritance problem he’s facing. However, as they delve into the mysterious St Clair history, they discover that the answers they seek lie not in the past – but in each other; and that there is nothing as simple – or as complicated – as a single, perfect kiss.