3、The old abandoned house at the end of the street had an eerie atmosphere, sending shivers down my spine, as if hiding some dark secret in its unknown past.
4、She received a mysterious letter from an unknown sender that contained a cryptic message, leaving her wondering about its sender's intentions and her own fate.
5、The young detective embarked on a thrilling journey to uncover the truth behind a series of mysterious disappearances in the small, secluded town, where everyone seemed to have an unknown motive.