Tennis player turned coach Tashi has taken her husband, Art, and transformed him into a world-famous Major champion. To jolt him out of his recent losing streak, she signs him up for a "Challenger" event — close to the lowest level of pro tournament — where he finds himself standing across the net from his former best friend and Tashi's former boyfriend.
Set in the 1980s, troubled youth Chan Lok-kwun accidentally enters the Walled City, discovers the order amidst its chaos, and learns important life lessons along the way. In the Walled City, he becomes close friends with Shin, Twelfth Master and AV. Under the leadership of Cyclone, they resist against the invasion of villain Mr. Big in a series of fierce battles. Together, they vow to protect the safe haven that is Kowloon Walled City.
Fresh off an almost career-ending accident, stuntman Colt Seavers has to track down a missing movie star, solve a conspiracy and try to win back the love of his life while still doing his day job.