The story starts off with two American astronauts on Mars Carter and Ed, Surveying the ground to find foreign objects. They find A organic looking object and Carter removes it from the ground, The ground caves in inside Carter turns on his flash light and sees ancient glyphs finds a door opens it unknowingly releasing an ancient evil left buried for thousands of years.
Flash forward two years later the aliens have infiltrated Wayne Tech they plant a bomb on the communication dish, Here is where we get to see the first introduction of a Justice League member in Batman shortly followed by Superman who has A traumatic psychic vision rendering him unconscious, the satellite blows up and Superman wakes up not knowing what has transpired batman confides in Superman telling him "over the past few months I have detected several security breaches in our global deep space monitoring network" Superman gives him a signal watch and says "call me if you need any help".
Later Superman is presented to the court by J. Allan Carter the astronaut that was on mars two years earlier as a viable solution to peace Superman vows "I solemnly swear to all of you, That I will continue to uphold the ideals of truth and justice not just for America but for all the world"
We also get the introduction of Wonder Woman and The Martian Manhunter aka J'onn J'onnz he was being held captive by the American government we find out superman's psychic vision were a result of J'onn J'onnz trying to telepathically reach out to him.