(I only own the characters in the Public Domain)
In 1968, a plane mysteriously disappeared without a trace above the Mid-Atlantic.
This disaster shocked the entire world, and drove Nite Owl II (alter ego Dan Dreiberg) and his partner Rorschach to see for themselves what happened.
When they reached the place the plane disappeared the Owlship (the vehicle they were traveling in), was shot down by some electrical weapon.
The duo managed to find the entrance to what seemed to be an underwater city, that was apparently called Rapture the two thinking this was connected entered.
On the inside they found that they weren't the only superheroes that ended up there, Spider Man (in his identity of Peter Parker) and the flame powered El Diablo had tried to investigate this bizarre place as well but now were resorted to fighting for their lives.
Both groups teamed up, and soon found that the inhabitants (which we later found were called Splicers) were in League with someone named Atlas.
The group was still going through smashing Splicers, when they ran into what appeared to be some guy in a massive diving suit.
The League attacked him and manged to defeat him, however before Rorschach could kill him a group of little girls attacked him.
As it turned out the creature (or as they called him), was their guardian and also wanted to find Atlas so they made a truce and set off to find him.
At some point they managed to find the people from the plane…although someone was using them as test subjects for something called ADAM.
The person who did this was Franky Fontaine, a mobster who seemingly died in 1960 at the hands of Jack Ryan only for the massive amounts of ADAM he took cause him to come back to life.
Fontaine turned out to have reprised his Atlas persona, as a way to control the Splicers as a means of capturing people that go near Rapture for his experiments, but when Nite Owl and co. showed up he fled like a coward causing the others to chase him.
The chase wasn't very long as he just encased himself in his own variant of ' suit and tried to kill them.
The fight lasted a long time, but it ended when they were finally able to crack the suit open and capture Fontaine out.
On their return to the surface, they found that an Interpol squad by an Inspector Clouseau had gathered outside, and they promptly carted Fontaine off to jail.
This was not the last time this group operated, one time they got back together to attack the notorious "Animal Farm" lead by a pig named Napoleon, and one more time after that when they went to Amity Island to capture one of the many sharks living in the water.