"The Sign of the Four" by Arthur Conan Doyle is a thrilling tale of mystery and romance. Mary Morstan seeks Sherlock Holmes' help after receiving mysterious pearls and a letter offering to reveal the truth about her missing father. As Holmes investigates, he uncovers a web of betrayal, hidden treasure, and revenge. Along the way, Dr. Watson falls for Mary, adding a heartfelt layer to the intrigue and danger.