Too Many Crooks Spoil the Betroth
Fantastic Four Annual #3 is, of course, mostly notable for containing the wedding of Sue Storm (Invisible Girl), and Reed Richards (Mr. Fantastic). It was a special event; never before had two superheroes gotten married. And as if to underscore its specialness, Stan Lee and Jack Kirby decided to throw in nearly every major Marvel hero and villain in 23 pages.
The story goes like this, Dr. Doom, enraged that Mr. Fantastic and Invisible Woman are going to have this special day, uses his 'High Frequency Emotion Charger' to cause every major villain to attack the Baxter Building at once. Fortunately, every major hero is in attendance. Why Dr. Doom has never used this device before or since is just one of a ton of plot holes that are glossed over in this issue. There's some notable omissions to the roster here - The Sub Mariner doesn't appear, probably because his own colorful history with the bride-to-be would have to be brought up, thereby pushing the page count beyond the 23 allotted pages; and the Hulk is absent, probably because the Emotion Charger would probably make him come in on the attack/villain side and he'd end up leveling the playing field... literally.
Speaking of the playing field, there's no way the heroes could normally win this one. There's villains here like Kang the Conqueror (who does nothing, but he's here), who could take on groups The Avengers single-handedly, and there's also whole teams like HYDRA and an Attuma's Atlantean army - so, were it not for extraordinary coincidence of the annoyingly convenient variety, the heroes wouldn't stand much of a chance.
Even so, the whole thing ends with a Deus ex Machina whereby a divine being gives Reed a machine to suck up all the baddies (and none of the goodies) and send them back to whence they came. Meaning the story pretty much sucks other than to show as many heroes and villains in as few pages as possible to try to seem epic.
Other gimmicks in this issue, including a terribly muddy looking 'photo' of the fourth dimension, and a cheesy breaking of fourth wall also fall flat, and the remaining 46 pages are all reprints - and some dubious choices at that, including the Impossible Man story, make this annual completely inessential. Reed and Sue get married, that's all that matters about this comic.