Fleming-Roberts, featured Lee Allyn, who had been the subject of an experiment with radiation, and as a result was invisible between midnight and dawn.
Allyn had no other superpowers, and the novels were straightforward mysteries in Weinberg's opinion,[1] though pulp historian Robert Sampson considers them to be "complex...[they] pound along with hair-raising incidents..full of twists and high suspense".
[1][2] The covers, all by Rafael De Soto, are "less satisfying" than the novels, in Sampson's opinion; Captain Zero is represented just by a floating robe and hood with glaring eyes—though the original artwork for the second issue, now in private hands, only shows the figures of a woman, and a man firing a gun, with no representation of Captain Zero.
[2] Each issue included a non-fiction section with crime anecdotes, and a department called "The Zero Hour" which narrated stories about anonymous crime-fighters—likely to be fabricated, according to Sampson.
The publisher was Recreational Reading, Inc, of Kokomo, Indiana, which was a subsidiary of Popular Publications in New York, where the editorial offices were.