If You're Reading This, it's Too Late | Pseudonymous Bosch

Cass and Max-Ernest are proud new members of the top-secret Terces Society, and can't wait for their first mission. Soon they are kidnapped by their dastardly enemies, discover the powerful and mysterious Sound Prism, and find themselves in a race against time to track down a monstrous manmade creature who guards the secret of eternal life.