Batman Becomes Bat-Baby
It's the Silver Age in Gotham City, so all the set-up you need will be right there in the first panel...
"Nails Finney" sounds more like a nemesis for Encyclopedia Brown than for Batman, but defeating Nails and recovering the gems isn't really the point of the story, as you've probably already figured out.
A renegade scientist! Framed for murder, now he prowls the badlands. An outlaw hunting outlaws, a bounty hunter, a Renegade.
Oh no! While I was reminiscing about bad '90s syndicated dramas (can you believe that ran for five years?), Garth was giving Batman an eerie bath! What will it do to him? You may be surprised! Unless you looked at the cover or the splash-page to this story. Then you know exactly what's going to happen.
*Gulp* Given the normal course of Silver Age logic, I'm kind of amazed the machine didn't somehow shrink his clothes along with him. So kudos to you, Bill Finger, uncredited writer of this story we think. Oh, and in case you were wondering, Nails, Renegade and the gang got away while Robin was gulping.
"I dreamed it, but I never dared hope!"
"And this picture of Batwoman getting out of a car with no underwear on. Printing it pierces my heart with agony, but the public must know!"
So Baldy McPipe up there prints the photos, and the citizens of Gotham moan about poor Batman's career being over while Nails and Renegade gloat about turning Batman into a laughing stock.
Meanwhile, in the Wayne mansion...
Here's our first look at the rejuvenated Batman sans costume. Not creepy in the slightest. Robin the High-Waisted Wonder looks like he's coming up with a brilliant idea, but I assure you he isn't. He's just wondering when they started printing telephone books in hardcover.
"And my adult-sized head!"
Are you sure you're still thinking like an adult, Bruce? Because that is some twisted logic right there. If somebody calls you something insulting, you prove them wrong by dressing like that something? By that logic, I would have spent most of college dressed like a Queen. (Even more than I already did.) I think he just wants to justify wearing his OshKosh Bat'Gosh overalls. Giant Bobble-Head Robin is stunned. (Or possibly turned-on by Bat-Baby's luscious lips. But let's go with stunned.) It may work, though. Batman's whole schtick is to strike terror into the hearts of evil-doers, and Bat-Baby would certainly scare the hell out of me.
So Bat-Baby and Robin go on patrol. They don't find Nails, but they do stumble across three generic bandits making a getaway on a rooftop. Bat-Baby's short legs can't climb the fire escape fast enough, so he hitches a ride on a giant promotional helium-filled tire balloon, conveniently tethered nearby.
The whole "Batman's strength in Bat-Baby's tight little package" thing works for him, and he captures the criminals.
The Gotham Gazette runs it as a human interest piece, but the City News is unimpressed. "Meh. I guess he did all right. Superbaby would have done better."
It wouldn't be a DC Comics Silver Age story without the risk of secret identity exposure, so...
Turning off all the lights and staying quiet until she goes away is far too simple. Instead, Alfred lets her in and tells her Mawster Bruce is in the library.
Although it's not mentioned in this story, Kathy Kane is secretly the superheroine Batwoman, and describing her as walking "gaily" may be foreshadowing, forty-five years in advance. (But probably not.) Anyway, Kathy doesn't bother to take the two extra steps required to confirm Bruce's infidelity, since we all know shadows are always exactly what they appear to be. Instead, she gets pissed and storms out.
Yeah, your cousin. That'll ease all her worries, and replace them with a fresh set of worries.
Later, Commissioner Gordon tells Bat-Baby and Robin that local fence Swap Smith is pulling lots of cash together, presumably to buy Nails' stolen gems. Luckily, the Gotham City Department of Parks and Recreation decided that across the street from a shady pawn shop was the perfect place for a playground.
It's extremely popular with parents, who can leave their kids here unattended while they hock their wedding rings for grocery money. Be sure not to miss the World's Largest Swingset. With only two swings, there's plenty of room for your child, and no need at all for another child to wander dangerously into his path.
I include this panel for two reasons. To show Batman on roller skates, and to illustrate how in the Silver Age only criminals and renegades and pawn-shop proprietors smoked cigarettes. Innocent background folks and conscience-plagued newspaper editors, like all good-hearted people, smoked pipes.
I included this panel simply because it's awesome. Feel free to copy it and use it somewhere out of context; it's even funnier that way.
Having been kicked full-force in the chest by the power of a 220-pound man concentrated into toddler-sized feet, this was, unsurprisingly, the final appearance of Garth the renegade scientist. So let's pause here to reflect on the fact that the man invented a machine that could reduce you in age while keeping your mental faculties, physical strength, and agility intact, and rather than selling it and becoming fabulously wealthy, he used it as a back-up plan in case his gem heist went awry. I guess that's why they called him...renegade.
Either that word balloon is pointing to the wrong person, or Robin is being unusually pessimistic. Also, what's with the wooden slide in the storage warehouse? Wouldn't that make getting crates up to the second floor unnecessarily difficult?
What kind of warehouse is this, anyway, that has fully-stacked bookcases, hobby-horses and massive harps lying around, unpackaged? Oh, right, it's a Silver Age Gotham City warehouse, I forgot. There's probably a thirty-foot high working typewriter and a robot gorilla around somewhere too.
That was your costume? I thought you were just glad to see me.
"Ha ha! Oh, Batman, you're a riot! I love it when you describe something as it literally happened but phrase it like you've made a joke! So, uh, hey, just asking, but, why are you still wearing the plastic costume?"