Call of Cthulhu Starter Set - Rules of Play says:
This Starter Box contains everything you need to start playing Call of Cthulhu—the tabletop roleplaying game of mystery and horror. Players take on the role of investigators of mysteries, uncovering dark secrets, encountering strange monsters, and thwarting sinister cults. Together, you and your friends create and develop a story in which each of your characters plays a leading role, which could be foiling some dastardly plot or stopping horrors from beyond space and time!