The phrase "mysterious alien world" refers to a place or thing that is unknown, strange and difficult to understand. It could be referring to an unexplored planet in outer space, a new discovery in science or even a different culture on Earth. The term "alien" implies something foreign or otherworldly, suggesting there may be secrets, hidden agendas or unknown factors at play. Overall, the phrase conveys a sense of curiosity and intrigue, inviting further exploration to uncover what lies beneath the surface.