"The Grown-Up Boy Wonder"
When Bruce Wayne and Dick Grayson examine a box which Superman found floating in outer space and left with them until he returned from a current mission, Dick accidentally causes it to open and spew forth a gas that ages him to a young adult. The two are unsure of what to do in Superman's absence, but the Bat-signal draws Batman away to a jewel robbery in Gotham being committed by the Daredevils, ex-acrobats turned to crime. Batman vetoes Dick coming along as a second Batman, saying that he has a lot of mental growth to do yet. But Dick sneaks on the "Owlman" costume that Bruce had stored away for a masquerade party, grabs a lift on the back of the Batmobile, and hurries away with Batman to the scene of the crime. Batman angrily thinks that he'd spank Dick, if he wasn't so big; the Daredevils manage to make a getaway, and Owlman, misgauging his weight, almost falls to his death when a flagpole breaks in his hands. Batman, saving him, angrily berates him for "acting like a kid--still rushing ahead without thinking!"
Dick begins to see the disadvantages of living in an adult body, such as his sudden cut--off from all his young pals and virtual isolation from the outside world. But, still confident he can fight crime as a man, he becomes Owlman again, tracks the Daredevils to a prominent fence's lair, and promptly knocks himself out by not ducking under a low ceiling beam. The crooks unmask him, but cannot place his adult face. Dick admits that he still has a lot of growing up to do, and Batman allows that if he can admit that, he isn't a kid anymore. Batman and Owlman go outside, tear into the three Daredevils, and bring them down. Shortly after the crooks are carted off, Dick faints, and awakens in the Batcave as a boy again, the effect of the gas being temporary. The Daredevils, in jail, vow to find out who the Owlman really was, not knowing they have a long wait ahead of them. And Dick Grayson returns to school, eager to get back with his friends.
-Note the trio in this story are referred to as the The Daredevils but bare an incredibly striking resemblance to the golden age characters the Three Devils. Not only do they have similar attire, they have identical origins, motifs, and even use the same fence, Frankie, to unload their stolen jewelry.