sentences:  Using an illegal time-jump device, Boris travels back in time to July 16, 1969, to kill the young Agent K. With history altered so that K is now long-dead, only J's own memory is somehow completely unaffected, and no one else from the Agency understands his obsession with K until Agent O, the new Chief of MIB following Zed's death, deduces there has been a fracture in the space-time continuum.With K gone, the ArcNet was never deployed, and present-day Earth is defenseless from a subsequent Boglodite invasion.Knowing from the Agency's records Boris will commit a murder there in 1969, J uses the same device to travel back in time to July 15, 1969, and goes to Coney Island to kill Boris and save K and the world.