Starling House by Harrow, Alix E.

Opal Gravely has spent her life obsessed with the mysterious Starling House – but when its reclusive heir offers her a job, she discovers there may be monsters lurking within. This is a sweeping, Gothic fairytale from Hugo, Nebula and Locus Award-shortlisted Alix E. Harrow, author of The Ten Thousand Doors of January.