'An underwater treasure-chest to be slowly unpacked, full of things I adore: nosy and loving families, epistolary romance, gorgeous worldbuilding, and anxious scholars doing their best to meet the world with kindness and curiosity' Freya Marske, author of A Marvellous LightThe charming conclusion to the Sunken Archive duology, a heart-warming magical academia fantasy filled with underwater cities, romance of manners and found family, perfect for fans of Emily Wilde's Encyclopaedia of Faeries.Former correspondents E. and Henerey, accustomed to loving each other from afar, did not anticipate continuing their courtship in an enigmatic underwater city. When their journey through the Structure in E.'s garden strands them in a peculiar society preoccupied with the pleasures and perils of knowledge, E. and Henerey come to accept--and, more surprisingly still, embrace--the fact that they may never return home.A year and a half later, Sophy and Vyerin finally discover one of the elusive Entries that will help them seek their siblings. As the group's efforts bring them closer to E. and Henerey, an ancient, cosmic threat also draws near. . .Praise for Sylvie Cathrall:'With its gorgeous underwater setting and whimsical academic sensibility, A Letter to the Luminous Deep is a strange, epistolary wonder.' Mary McMyne, author of The Book of Gothel'A shimmering, delicately crafted delight. . . Readers looking for heart warming romance and scholarly mystery against the backdrop of a wildly imaginative world will be charmed' H.G. Parry, author of The Magician's Daughter'Cathrall's debut caught me up on a wave of whimsy and swept me away with its charm. A story to be cherished' Lyra Selene, author of A Feather So Black'A Letter to the Luminous Deep is a fascinating and charming story told in a uniquely elegant voice. A watery wonder of a novel! I loved it.' Louisa Morgan, author of A Secret History of Witches 'A Letter to the Luminous Deep is like nothing I've read before. The heartfelt intimacy of the epistolary narrative, juxtaposed with the magnificent oceanic world-building, results in a novel that is at once deeply human and mind-bogglingly imaginative. Both the setting and the story are exquisite, but it was the lovingly crafted voices of the characters that kept me hooked from beginning to end' Megan Bannen, author of The Undertaking of Hart and Mercy