Das Tattoo - Tödliche Zeichen: Karl and Paula work as specialist divers in Vienna, while their former friend Fred runs a diving school in Croatia. While surveying Vienna's underground, Karl and Paula come across a system of catacombs in which they discover valuable burial objects and a mummified corpse with numerous tattoos. When Karl has an accident during his explorations, Fred is asked for help by Paula. Neither of them suspect what they will soon be involved in.