Lars was a sort of special agent for the Martian Supreme Council, who took note of Earth's H-bomb activities (this was the early 1950's, after all) and sent their man to investigate. Since the Martians, as well as the inhabitants of Venus, had gotten rid of their spacecraft years before, one had to be cobbled together in a hurry so that the obviously-warlike humans could be studied. Once here, Lars took it as his ongoing mission to not only keep our bloodthirsty tendencies in check, but also to look out for us whenever various cosmic threats raised their heads.
Jerry Siegel is believed to have created and written this brief series, while the art was provided by Murphy Anderson. In #11, a science-fiction backup story with art by future Marvel great Gene Colan appears.
Lars of Mars would resurface again, briefly, in 1987 when Eclipse Comics would republish these two issues in a 3-D format.