Set the Stars Alight by Amanda Dykes

Reeling from the loss of her parents, Lucy Claremont discovers an artifact under the floorboards of their London flat, leading her to an old seaside estate. Aided by her childhood friend Dashel, a renowned forensic astronomer, she starts to unravel a history of heartbreak, sacrifice, and love begun 200 years prior--one that may offer the healing each of them seeks.