Tidespeaker by Sadie Turner

'Do not speak unless asked a question. And do not refer to your predecessor. At all.'

Corith Fraine is a Floodmouth - her words can control water. She has spent most of her life in an elite magic institution, training for the chance to serve one of the realm's noble households. When she secures a post working for House Shearwater, an aristocratic family living on a wave-battered island, she knows what an honour this is. Until she discovers that her predecessor, her best friend Zennia, has mysteriously died.

If Corith is to avoid the same fate, she must learn to harness the wild, unforgiving tides while also catering to the whims of the glittering Shearwater siblings, who each harbour secrets of their own. But as Corith starts to unravel the conspiracies at the heart of the island, she finds herself drawn to the striking but unreadable youngest son, Llir.

With her loyalties pushed to breaking point, these treacherous waters may just pull Corith under.