A year after the death of his friend and partner Sherlock Holmes, Dr. John Watson resumes his medical career as the head of a clinic dedicated to the treatment of rare diseases. However, he soon finds that his old life is not done with him.
With his eyes fixed on the future, Watson faces an unexpected twist when Sherlock Holmes, who was presumed dead, resurfaces, forcing him to confront a buried secret from his past—one that lies hidden within his own body.