After a botched attempt at suicide, Nora King (Kathleen Crowley) revives and discovers that her building has no electricity or water. She soon realizes that Chicago is deserted when she wanders out into the empty, quiet streets. Stumbling over the body of a dead woman, she encounters Frank Brooks (Richard Denning), another person who has just recently revived after being beaten in a robbery.
With her new companion, Nora continues to try to find others in the abandoned city. Hearing music from a nearby restaurant, they come upon a couple, Jim Wilson (Richard Reeves) and Vicki Harris (Virginia Grey), who are drunk and admit they were incapable of joining the evacuation with the rest of Chicago's population. The group then continue to search the deserted streets, coming upon a car that will not start. Another survivor, Charles Otis (Mort Marshall), sees them and reveals that the same applies to all the other cars he has tried.
A growing apprehension takes hold as they begin to realize that they are alone with an unknown menace that has caused everyone to evacuate Chicago. Charles finds a newspaper in a hotel lobby that proclaims that a "mystery army" is attacking the city. In a panic, he runs out into the street, only to be killed by a death ray from a nearby alien robot.
While attempting to defend the city, the military, led by Lt. Gen. Wood (Arthur Space), sets up a command post. Although Air Force bombers are easily destroyed by the advancing invaders, the use of atomic weapons is contemplated. A group of scientists, including the chief research scientist (Whit Bissell), are finally able to work on a captured robot in order to find out if the alien machines have any vulnerabilities. While trying to escape the attacking robots, the small band is joined by Davis (Robert Roark), a psychotic killer who has his own plans for survival.
With danger all around, the group realize that the enemy is both within their group and from outer space. Several deaths occur as the tiny band flee for their lives from the alien menace. An army unit eventually arrives that is fully equipped to effectively dispatch the invading robots, halting the invasion.
The screenplay for Target Earth is based on the 1953 science fiction short story "Deadly City" by Paul W. Fairman, which first appeared in the March 1953 issue of If magazine under Fairman's pseudonym, "Ivar Jorgensen".
Principal photography began mid-July 1954 at Kling Studios, for a shooting schedule of a tight seven days that also included outdoor shooting. While set in Chicago, Target Earth was actually filmed in Los Angeles. Empty street scenes were filmed during early morning hours before normal traffic began.
Actor Robert Roark was given a role because his father was a large investor in Target Earth.
Even though a "robot army" is mentioned several times during the film, only one robot was constructed for the production, which was then used in all scenes to depict the invasion. When actor Steve Calvert, who played the robot, was not working on B films, he regularly worked as a bartender at Ciro's on the Sunset Strip. He also played the apes in Bride of the Gorilla (1951) and Bela Lugosi Meets a Brooklyn Gorilla (1952).
Target Earth was a typical product of 1950s filmed science fiction but could never rise above its low budget underpinnings. One of the few notable aspects of the production was that the film was one of the first to explore the subgenre of alien invasions, following the success of George Pal's The War of the Worlds (1953). Target Earth was also produced by Herman Cohen, making his producing debut, who would become one of the most prominent B movie producers of the 1960s. Director Sherman A. Rose, who was a prolific editor in both television and film, would go on to make only two other films.
TV Guide later rated it 1/4 stars, writing "The robots are just plain disappointing." David Maine of PopMatters rated it 6/10 stars and called it "a tight, engaging little thriller that focuses more on character than special effects."