Dedicating his life to the pursuit of justice, rookie police officer, Jung Ba Reum (Lee Seung Gi), is an honest man with an honest heart. Working at a local substation, Ba Reum is a steadfast officer who, together with his partner, Go Moo Chi (Lee Hee Joon), is always willing to do whatever it takes to get the job done. Finding true fulfillment in his work, Ba Reum is happy with the life he has made for himself. But when the nation is rocked by the ruthless murders of a crazed killer, his peaceful life takes a very dark turn. Gripped by fear, the nation slowly sinks into chaos as a psychopathic serial killer runs amuck. Always one step ahead of the authorities who chase him, the only sign the cops have of the killer’s presence is the grisly trail of chaos left behind. Determined to find this killer and bring them to justice, Ba Reum and Moo Chi eventually track them down. Standing face to face with the killer, Ba Reum manages to survive the deadly encounter but their meeting would change his life forever. Determined to understand what drives a person to such violent extremes, Ba Reum and Moo Chi begin a quest to understand how psychopathic behaviors develop. But their quest for the truth begins to raise some very poignant questions. Questions that lead them to wonder, where does one draw the line between far and too far? An action-packed thriller, “Mouse” is a 2021 crime mystery drama directed by Choi Joon Bae and Kang Cheol Woo.