The story takes place in the year 2025, 21 years after the events of the previous season when Earth has welcomed alien beings to live peacefully with the human race. However, peace is short-lived as the planet-conquering Troobian Empire turns its destructive attention to Earth. When the Earth's first line of defense, the S.P.D. A-Squad mysteriously vanishes without a trace, the protection of the planet falls to their replacements: the B-Squad Rangers, under the guidance of their dog-like alien commander, Anubis "Doggie" Cruger.