David Starr is new to the Council of Science. While in a restaurant, he witnessed a man mysteriously dieing while eating dinner. After some research, David figures out the man had died from poisoning by food that came from the Martian farms. David convinces the Council to let him try to infiltrate the Martian farms as a farmboy.
When he arrives on Mars, everyone is instantly suspicious of him because they know he is an Earthian. In Wingrad City, while looking for a job at the Farm Employment Building, he befriends a small, loud-mouthed man named John Bigman Jones, a famrboy who has lost his job at the Makain farm.

David has to defend himself against Griswold, a large farmboy working for Hennes, the satistic supervisor of the Makain farm. He works a deal for both himself and Bigman to be hired on. Benson, an agronomist for the farm, has been working on trying to figure out how the poisoning is working. His theory is that Martians are infecting only a few grains, which only kill a very small amount of people on Earth.

David, also convinced that there are Martians living in caverns below the surface, is determined to make contact to find out the truth. Little does he know that his deadliest foes are not Martians, but Humans.

David Starr - Space Ranger is the first book of six in the Lucky Starr Adventures by Isaac Asimov (originally writing as Paul French). It is a Science Fiction story that takes place when humans have moved out into the galaxy and inhabit many worlds (about 5,000 years from now). David Starr must figure out who is poisoning Earthians with Martian food, and why.