What could drive Lois Lane to dress up as Clark Kent? Well, some things are a slippery slope. And the Silver Age was slippery indeed. It all began when everyone was out of the office one day, and Lois had to answer Clark's phone... with his voice!
So now Clark's been given a rendezvous he can't possibly get to, so obviously, Lois must scoop him by raiding Jimmy Olsen's disguise trunk and indulging in a bit of cross-dressing. There's nothing wrong with that!
Except as soon as Clark--what's the feminized version of Clark? Clarkette? Clarka? Clarke? Linda?--reaches the abandoned lighthouse (in the Superman universe, there's no need for lighthouses anymore because everyone's become dependent on last-minute rescues), she gets knocked out!
When the police call her office to check on her story (is she under arrest or something?), Clark answers and throws her under the bus!
Sorry Lois, but it's kind of hard for you to deny you've been acting peculiar. Have you READ your series? Anyway, the next day, Lois is spending her high-salaried time opening up fan mail for one specific article people particularly enjoyed with her gold letter opener, a gift from the extremely high-salaried police commissioner for her help capturing "Killer" Meigs (CRUCIAL CLUE: He swore revenge!). I know a lot of journalists and yes, I can vouch for all this to be an accurate portrayal of the profession. But then...
Caught with a knife and a slashed picture of Superman, her colleagues come to the only possible conclusion, that she's gone mad. Clark immediately offers to bring her to a psychiatrist he knows, which becomes even more urgent when he finds poison in her purse, something she apparently kleptoed from a police safety lecture the day before. "In my condition, I might unknowingly take a deadly pill!" Yes, get some help, Lois!
After listening to her talk about Superman for a few minutes and staring at her intently, Dr. Blake offers a sound diagnostic: She's having a nervous breakdown on account of Superman refusing to marry her. OF COURSE. Also, if she doesn't do something, she'll soon start to hear voices and end up in a mental hospital. BECAUSE THAT'S HOW MENTAL ILLNESS WORKS. Good thing there's a cure: He has her read a book about Ben-Hur so she can shift her admiration to a different hero. Psych students TAKE NOTE! And she enjoys the book loads, it seems to be working. But the next morning, Clark and Lucy show up to find the book was just blank pages. She imagined it all. (So Dr. Blake mistakenly gave her a blank book? Who even HAS a blank book?) They leave, because that's what you do when your friend/sister is having a breakdown, and immediately, Lois starts hearing voices.
Lois does what anyone suffering from hallucinations should do: Go out for a drive. Uhm... So what's REALLY going on here? The truth:
That's right, this is "Killer" Meigs' revenge scheme, going after Lois' sanity from behind bars. To accomplish this he's bugged her home, car and office and set up an intercom to do the voice thing. But he's also kidnapped Clark Kent, replaced him with a double, counted on the fact Lois would go to the lighthouse in Clark's stead, counted on Lois having a knife in hand when she went to the stock room, put poison in her purse, sent her to a fake psychiatrist, gave her a book printed in disappearing ink... The most surprising thing, though, is that Superman wasn't behind the whole thing. Still, he did kind of sacrifice Lois' well-being for his secret identity. I mean, she's been driven to suicide just because he couldn't think of a way to discreetly use his powers so he WOULDN'T be taken by a couple of bargain basement thugs.
So Lois finally clues in that it's all a fake because Clark paid tribute to his dead father in his Father's Day article?! Uhm... That seems like a nice thing to do. But it breaks the spell, so dupe-Clark (I gave you two fake Clarks this week, you better show gratitude) has to suicide her out a window. Because this is the Silver Age, the thugs are murdering Clark at the same exact time, freeing him to last-minute-rescue Lois as Superman.