The novel explores how shadows of the past affect the present, with Greta's dementia becoming a key that unlocks doors to dark secrets from World War II. It shows how trauma and guilt are passed down through generations and the importance of confronting one's history.

The complex relationship between Tom and Greta is overshadowed by unspoken secrets from the past. As Tom deals with his mother's illness and emerging revelations, he discovers a new side of Greta, testing their deep but complicated mother-son bond.

The story explores love against the backdrop of racism and bigotry in post-World War II Germany. The mysterious girl in the photo and Greta's silence point to a forbidden love and the challenges faced by people of different backgrounds during that time.