An alien disguised as a human woman must protect Earth from an intergalactic threat while hiding her identity from her husband.

My Guardian Alien revolves around the story of Katherine's happy, doting, and ideal family. However, their peaceful life will turn upside down when a shooting incident kills Katherine. This leaves Carlos and Doy devastated. One night at the funeral, a mysterious pod accidentally falls on Earth. It contains an alien, which suddenly takes the form of the dead Katherine. Will Carlos and Doy accept this strange woman who looks exactly like their lost loved one? What is the alien's mission on the planet? How can she fit into the world of humans where there is love and emotions?