Following the defeat of the Space Pirates in Metroid Prime 3: Corruption, the Galactic Federation began work on Project Golem, an effort to better equip their soldiers to combat the Pirates. They created Mechs, armorsuits based on the design of Samus Aran's Power Suit, to be worn by the Federation Force's members. Part of the training is a game of Blast Ball, the outcome of which will determine a Marine's acceptance into the Force. During the game, the Force is deployed to the Bermuda System on an archaeological survey expedition led by General Miles. They discover that the Pirates have overtaken the system's three planets: Excelcion, Talvania and Bion, and begin to thwart their nefarious plans with help from Samus Aran.
The four Marines have color-coded visors: red, blue, yellow and green. None of the four characters have any set names or personalities. They do not speak during missions; the only time they will speak is through pre-recorded messages. The gender of their voice can be chosen in the game's Options.
The Federation Force are the only individuals in the Metroid series who have ever defeated Samus Aran in battle.