Lin Chen, who has a dream of adventure, accidentally met Tang Youran, an expert on legendary ruins, the mysterious thief Hu Fei, Ouyang Sheng, the second-generation rich man, and the mythical beast "Mao Qiu", and accidentally stumbled into an unprecedented adventure to find the "Lost Key". On the way, they shuttled between modern cities and ancient secret realms, solving numerous puzzles and confronting many obstacles from tomb robbing groups, ruins guardian forces and mysterious alien creatures. The outstanding and diverse team members gradually revealed the ultimate secret of the "Gate of Mountains and Seas" while complaining about each other and growing up in each other's complement, and also witnessed the power of friendship, dreams and courage. In the end, a shocking adventure across mountains and seas came to an end - they not only changed their own destiny, but also wrote a wonderful legend belonging to young people.
