In Goodbye, Mr. Cool, Ekin Cheng takes on the role of Dragon, a talented former hitman who decides to leave behind a life of crime to start anew. He begins working as a waiter at a blue-collar café, seeking to regain peace and normalcy in his life.

However, everything changes when Dragon's ex-girlfriend steps into the underworld and becomes its queen. She is determined to lure him back onto the criminal path he once left behind. Despite Dragon's resistance, the allure of the past and past love proves too strong to resist.

The battle between loyalty to reform and the temptation of the past thrusts Dragon into a dangerous adventure, where he must face the dangers and challenges that the criminal life brings. Goodbye, Mr. Cool is not just an exciting action movie but also a story of the struggle between right and wrong, hope and despair.