Diàochá rényuán fāxiàn le yì tiáo yǐnmì de tōngdào.
The investigators discovered a hidden passage.
Tips
usage
隐秘 emphasizes being deliberately concealed or hard to find. Compare with 秘密 ('secret' as a noun or adj.) which is more general. 隐秘 has a more literary feel and often describes places, activities, or lifestyles.
