While the annual Justice League of America/Justice Society of America team-ups were the highlight of many a summer for comic book lovers, they did follow more or less a formula:

A crisis is revealed – usually threatening the existence of one or both worlds – and our heroes gather, split off into smaller teams, regroup for a final battle, vanquish the foes, right the wronged and agree to meet same time next year with a hearty wink and a wave.

Shake, lather, rinse, repeat.

That’s not a knock. There were so many heroes on both teams to choose from, and DC’s stable of writers, for the most part, were so inventive, the stories never got stale.

During his tenure as writer for “Justice League of America,” Len Wein pushed it further, resurrecting such Golden Age greats as the Seven Soldiers of Victory and the Freedom Fighters.

One side-effect of these mob stories: Suddenly it seemed as if the Justice League and the Justice Society couldn’t carry their own team-ups anymore. There had to be even more heroes in the mix.

But a publishing quirk in 1974 would interrupt that dynamic, briefly, and result in one of the most heartbreaking stories in the Justice League’s and the Justice Society’s combined histories.

As Len Wein notes in his introduction to “Crisis on Multiple Earths Volume 3,” by the time it came around for him to pen what would be his third and last JLA/JSA team-up, DC had switched over many of its books to “100-Page Super-Spectaculars.”

For 60 cents – granted, a huge sum back then for certain kids (me) – you got a 20-page original story, plus approximately 80 pages of reprints and back-up features, give or take a few ad pages.

For a generation of JSA-lovers born in the 1960s who had been living off the annual team-ups, the “Justice League” spectaculars were glorious treasures – reprinting actual Justice Society adventures not seen in decades. Remember, this was a time when no one had even thought of trade paperback collections, much less hard-cover archives. These issues truly were spectacular.

But as Wein noted, with this format, “Justice League” was being published bi-monthly in 1974 – and a two-part story would eat up a third of the “Justice League” stories for the year.

For you and me, this isn’t a problem, but Wein and DC, it resulted in the first and only done-in-one team-up, “The Creature in the Velvet Cage,” in “Justice League of America No. 113,” cover-date September-October 1974.

Across more than a decade of annual team-ups, the Justice Society had remained pretty much the same – gaining two members (Robin and Red Tornado) and losing two members (Black Canary and Red Tornado). But here was an adventure that actually pulled back the curtain on the private life of one of its founding members with devastating effect.

Wein was curious, wondering why Sandman gave up his garish yellow and purple togs for his original trench coat and gas mask.

Here, after the combined might of the Justice League (Superman, Batman, Green Lantern and Elongated Man) and the Justice Society (Wonder Woman, the Flash, Sandman and Hourman) defeat the Horned Owl Gang on Earth 2, an alarm goes off. Sandman takes off in a panic. The rest of the heroes follow, to Sandman’s secret lair, where they find a glass cell destroyed – its occupant having escaped.

Sandman confesses: The monster he caged, the behemoth now on the loose, is his own ward and partner Sandy Hawkins, the Golden Boy.

Years earlier, they had been testing an experimental weapon – “a silicoid gun” – when the weapon malfunctioned and transformed Sandy into a sand-based monster.

Now I don’t know about you, but when I test an experimental weapon, I like put some distance between the two of us – a lead shield, a sand dune, maybe even another state. Sandy was apparently staring down the barrel so closely, he could read the registration.

Sandman was able to subdue Sandy and imprisoned him in a special cell in which gases left him pretty much comatose. Out of guilt, he abandoned his garish duds and returned to his Golden Age apparel.

Our heroes split into smaller teams to recapture Sand. There’s a bit of unexpected comedy in these side-quests, perhaps to balance out – or to punctuate – the somber nature of the ending. A bride throws pies at Sandy; the muscleheads at “Machismo Beach” try to impress their girls by jumping Sandy and get tossed aside like dirt. Come to think of it, that bit might have been a riff on those Charles Atlas ads that were so ubiquitous in comics then. Here the bully is tossed aside by sand itself.

Sandy hasn’t been terrorizing strangers for the fun of it – he sensed a disturbance in the fault lines across the city and was trying to stop an earthquake that would cause catastrophic damage.

And here we get a fun bit of super-heroics you’d only find in pre-1980s comics or “Avengers” films: Superman borrows Wonder Woman’s golden lasso and sews up the fault line with his super-strength!

The crisis averted, we get our kicker and it is brutal: Sand reveals he came to his senses shortly after being transformed – but the gases in the cage prevented him from telling Sandman.

Wracked with guilt, Sandman stands alone, trying to grasp all the years he cost his ward.

There’s no happy ending, either, just a hopeful one, as Wonder Woman offers to call upon Amazonian technology to cure Sandy. But it’s clear Sandman will carry this failure with him the rest of his life.

“The Creature in the Velvet Cage” remains a powerful story, and I would argue the most influential 1970s Justice Society story to such modern-day writers as James Robinson and Geoff Johns. This story proved the Justice Society was more than capes and cowls who happened to resemble the Earth 1 heroes. They had their own histories, stories, foibles and flaws.

Sandy would regain his mortal form, but the repercussions of this story would haunt him and the team for years in the “JSA” title.