In the highest prison on the moon, the vicious Bergroldo Boris (Jemaine Clement) escaped from prison. He committed an evil crime in 1969 and was eventually sent to prison after young K (Josh Brolin) cut off one of his arms. The purpose of his escape this time is to travel through time and space to kill K. At the same time, J (Will Smith) and K (Tommy Lee Jones) continue to deal with the chaos caused by various aliens. Because they remain silent about Boris's case, the two good partners have a gap in their hearts. On a brand new day, J finds that K has disappeared, and almost no one around knows K. At this time, K had been killed by Boris 40 years ago, and the A network he established no longer exists. At this critical moment, the Bergroldo invaded the earth in a large-scale manner. In order to protect his home, J must travel through time and space to change history again...