H
Helen Dunmore
Ingo
When her brother disappears, Sapphire discovers Ingo, an underwater world of merfolk. This fantasy series explores the bond between siblings and the mysteries of the ocean, blending adventure with the allure of a hidden realm.
The correct reading order for the main series is Ingo, The Tide Knot, The Deep, and The Crossing of Ingo. There are also companion books that expand on the world.
Yes, there is a companion novel titled 'Stormswept' which explores events from a different character's perspective within the Ingo universe.
The Ingo series is a standalone fantasy world and does not directly connect to Helen Dunmore's other works for young readers or adults.