The book "The Thirteenth Letter" by Natalie Sumner Lincoln is an exciting detective story that unfolds in modern New York. The main character, journalist Emily Grove, receives a mysterious letter that indicates the possibility of a secret society. During the investigation, she finds herself in the middle of a tangled web of betrayal, intrigue and secrets that could affect the fate of the whole world. Mysterious symbols, ciphers and dangerous events add tension to every page of this exciting book. "The Thirteenth Letter" is not only a book about a detective investigation, but also about faith in justice, the power of friendship, and the importance of one's own truth.