'The Illustrious Prince' is a mystery novel written by E. Phillips Oppenheim. In an era of international intrigue and suspicion, the Emperor of Japan sends his cousin, Prince Maiyo, on a critical mission to uncover the true motives of the American battleship fleet's world cruise. As the Prince travels to London, he finds himself caught up in high society, attracting the attention of Miss Penelope Morse, an alluring American woman with a mysterious past. But when two American diplomats are murdered, all eyes turn to Prince Maiyo as the prime suspect. As the evidence mounts against him, the Prince faces a perilous fate.