While trailing Forest Ranger Charles Carter, who is suspected of permitting lumber man Henry Mitchell to cut restricted timber, Gene fires at a dangerous mountain lion and apparently kills Carter. Actually, Bill Wright, Mitchell's associate, killed Carter because the ranger had discovered tussock moth infestation in the forest, and if the infestation was not reported, the trees would die and have to be cut, thereby profiting Mitchell and Wright. In order to compensate the best he can, Gene sells his sportsman's camp and gives the money to Carter's daughter Helen . En route to Texas, Gene discovers the infestation and is assigned by the Forest Department to supervise the program of spraying the area with DDT from the air. After the first day of spraying, the DDT is blamed by furious stock men for the many animals found dead of poisoning.

Daniel Boone leads settlers into Kentucky, but must battle Shawnee Indians who have been persuaded by a French renegade that Boone and the settlers are there to kill them and steal their land.

A Chicago gang led by Slade carries out an audacious brokerage robbery. Lieutenant Bill Mason takes the case, continuing his friendly-enemy relationship with crime reporter Ann Rogers. One gang member is caught; eventually, others follow. But Mason hasn't a clue to Slade, principally because he's unaware she's a woman.

A private detective, soon to enlist in the army, is drawn into one final case when his police officer father is killed in the line of duty. Soon his prime suspect is murdered as well, and he finds himself framed for the crime. As more witnesses get murdered, he finds himself on the run from both the police and former Prohibition violators who seem to have found a new racket.

Art curator George Steele experiences a train wreck...which never happened. Is he cracking up, or the victim of a plot?