An article on Comicmix.com emphasized the game’s focus on teamwork between the two characters: in single-player mode, the AI controls the other character aside from the main character, while the game can be played in Local Co-op with two players as both characters. The article also mentioned there would be no online Co-op mode.
The End Is Nigh takes place during the Crimebusters era (renamed Watchmen for the film adaptation), when Rorschach and Nite Owl II were crime-fighting vigilantes before the Keene Act passed in 1977. Upon hearing a police bulletin, Nite Owl and Rorschach make their way to Sing Sing prison to help quell the rioting that has erupted there.
Once there, they find out the riots were a ruse to cover up the escape of The Underboss, a crime lord. They make their way to a bar, the Rumrunner, and question one of the patrons to find out who orchestrated the escape. They find out Jimmy the Gimmick was behind it, so they chase him down the docks to an abandoned amusement park. They corner him on the tracks of a roller coaster, where someone activates the carts to try to kill Jimmy. Nite Owl holds them back with his grappling hook but a mysterious sniper shoots the cable, causing the carts to fly right into Jimmy, causing him to be severely injured. Before his fall off the roller coaster, Jimmy managed to tell them the Underboss is in his old hideout in the sewers, so after calling an ambulance for Jimmy, that is where Nite Owl and Rorschach go.
They don’t find him, but they do find a missing FBI associate director, Mark Felt, tied up and bleeding heavily, seemingly tortured. He tells them that someone (who the heroes presume to be Underboss) means to kill two reporters, Bob Woodward and Carl Bernstein, the would-be informers of the Watergate scandal. Upon leaving the sewers, Nite Owl and Rorschach are ambushed by the police, Rorschach chiming in that they have been set up.
They fight their way through them to get to the construction site where Felt told them Underboss is, only to find that the reporters are already dead. Underboss claims he had nothing to do with it, that he was set up. The duo chases him up the construction site and manages to corner him, but the Comedian snipes him from afar. It turned out the Comedian was the mastermind behind all the events, working on behalf of the American government to cover up the Watergate Scandal (a reference to a comment made about Woodward and Bernstein by the Comedian in both the graphic novel and film).
In Part 2, Rorschach sets on the trail of a missing girl named Violet Greene. With a reluctant Nite Owl in tow, they infiltrate a seedy strip club, where they discover that the kidnapper is the Twilight Lady, an old flame of Nite Owl’s. They break into her mansion (which acts as a high class brothel) and discover that Violet enjoys being a prostitute, however Rorschach claims that she may have been brainwashed. Nite Owl says that if Violet is there of her “own free will” then there is nothing that they can do. Rorschach disagrees, and the pair chase Twilight Lady through the mansion, before she is thrown into a skylight. The ending of the chapter depends upon the outcome of the final battle (between Nite Owl and Rorschach). If Nite Owl wins, then he throws Rorschach through the skylight and rescues Twilight Lady before ordering her to leave town and never return. If Rorschach wins, however, he throws Nite Owl to one side and shoots Twilight Lady with the harpoon gun, killing her. Whichever character is the victor, the game ends with the partnership between Nite Owl and Rorschach being severed, and Nite Owl teaming up with the Comedian to quell a riot (an event which is depicted both in the graphic novel, and the film).