Helen Dunmore 
Tide Knot [EPUB ebook] 

The underwater world of Ingo is once again brought to life in this spellbinding sequel. Sapphy, Conor and their mum have moved away from the cottage by the cove, away from the memories of their father. But Sapphy can’t adjust to her new life and is increasingly drawn back to Ingo and to her Mer friend, Faro. Now the undersea world is becoming more dangerous, and as its power grows, both Sapphy and Conor are called to its depths to take on the might of Ingo’s tides.