The ancient gate in modern physician Lin Zhou's backyard connects to the era of the Three Kingdoms. Plagued by gout, Cao Cao uses a passage opened by the ebb and flow of yin and yang to cross into another world and seek medical treatment. An ancient gate links two worlds, and warlords from Cao Cao's and Liu Bei's factions gradually discover the secret of the mysterious gate, each seeking to spy on or seize control of the passage through time and space. While treating the illnesses of people from the Three Kingdoms, Lin Zhou must also maintain the passage, which is on the verge of depletion. Navigating between powerful warlords, he struggles to protect his clinic and preserve the balance of the ancient gate between two eras.