The Absence, formally Una Nemo, was a Gotham City socialite and one of the many "Bruce Wayne Girls" that Alfred was fond of. With her relationship with Bruce Wayne never flourishing because of his constant knack of keeping her at arms length rather than embracing her, she was left alone and abandoned.
Some time later, Nemo was having a good time at yacht party while a jewel heist was being committed. Nemo fought back but the thieves shot her at point blank range in the forehead. Her body was found two weeks later and put to rest. Six weeks after that, her grave was robbed, and being that Bruce Wayne had announced he was the finacial funder for Batman, Commissioner Gordon calls the Batman of Gotham, Dick Grayson and Robin (Damian Wayne) due to the Wayne's connection. After investigating the grave, Gordon receives a call that Nemo's body was left on the doorsteps of the GCPD.
On the scene, an investigator realizes that the body (missing a ring finger) is not that of Nemo's. Later the figer is left at GCPD, missing it's nail. Dick realizes that a pattern is forming, a grave without a body, a body without a finger, a finger without a nail. Realizing the only thing that could be taken from a nail would be the polish, Dick figures out that the polish is a clue. Sure enough, the polish is a time release flammable agent, causing the corpse to burst into flames. Testing the compound, Dick goes to find the scientist who created it, and finds an invitation to a wedding, which turns out to be a trap. The scientist, Dick and Damian think they're rescuing people at the wedding from a deranged minister who is holding a man at gunpoint. Damian slaps the minister with an upside down cross but Dick orders Damian to retreat to the roof beams of the church where the wedding was being presided. While avoiding gunshots on the roof beams, the Dynamic Duo learn that the scientist is a chemical engineer who specializes in flammables and advertised it as a hobby. His services were contracted by a disguised voice on a phone.
Suddenly, the shooting ceases and the minister reveals himself (actually herself) as Una Nemo in disguise. Nemo still has a giant hole through her head and thanks Batman for finally noticing her. She introduces herself as The Absence, and hopes he'll see what he was missing in her. She explains to the Dynamic Duo on how she miraculously survived that fateful night. After being shot and thrown into Gotham River, Una begins to contemplate her existence, the universe and her relationship with Bruce. After arriving home, she apparently has a machine that can scan her and it states that she is currently suffering from Dandy Walker syndrome. The machine indicates that even though she wasn't completely unharmed, the increased flow of oxygen to the hole in her head where her brain should be, will have dangerous side effects. One side effect that Una suffers from now is insomnia. Later, she attends her own funeral disguised with a shadowy veil, hoping to reveal her stable condition to everyone including Bruce. Unfortunately, she soon realizes that no one was upset by her death and Bruce didn't attend either since he was trapped in a constant loop in the time stream. After Bruce's return to the present time and his revelation that he has been financing the Batman, Una decided to leave a trail of clues for Batman to follow so that he would report it back to Bruce. As for her henchmen, Una recruited people who had nothing and were just absent or forgotten as she was.
After revealing her scheme, Una activates explosives in the church and escapes. The Dynamic Duo save as many hostages and henchmen as they can carry while Una pays Vicki Vale a visit. Una introduces herself with a large pair of scissors in her hand and presents Vicki with a bloody doggy bag labeled "Girlfriend's Body Parts". Dick figures that Una will go after any woman in Gotham that Bruce has gone out with publically. Batman and Robin arrive at Vicki's apartment demanding to know what Una has done with Vicki. Una assures them that Vicki is safe for now. Dick tries to deliver Bruce's heartfelt explaination as to why he was never there for Una but Una ignores Bruce's apology and assumes that he is with someone else now. Una then removes a nose piece which releases an unnamed knockout gas that causes the Dynamic Duo to fall asleep but it has no adverse effects on Una.
When the Dynamic Duo awake, they discover that they are fastened back to back with a drill facing each of them. Una then explains that in order for them to convey the proper message to Bruce on how she feels, they must know how she feels. Una starts the drills and points out how her death trap works. The chairs that the Dynamic Duo are fastened to, will slide back and forth, enabling one of them to drive the drill deep into the other's head. Damian decides to mock Una rather than giving her the satisfaction of forcing them to kill each other. Una admires Damian's unflinching determination but she then wonders if Batman has the same loyalty to Bruce or are they as disposable as she was? As the drills get closer, Una taunts Dick that no one is coming to save him but Dick lets her continue bantering while he removes his straps with a small blade.With the drills moving ever-closer, Batman asks Una if she's really intends to hurt them because she was hurt. The drill bits make contact with Dick and Damian, but crumble to pieces as Una explains that they were made of paper machete. Una reveals that everything was a distraction so that no one would be aware of her people killing the robbers that originally shot her in the head after killing her friend, Terri. She catches a batarang thrown by Damian and heads toward an open window, raises a gun to her head, pulls the trigger, and falls to the ground below but the Dynamic Duo examine the street with no sign of a body.
Back at the Batcave, Alfred tells the Dynamic Duo that the chemist was found alive in a doughnut factory, which demonstrates that Una is not without humor or mercy (doughnuts have holes in the middle). Dick knows that Bruce cares about the women he sees, but he never had the most humane priorities concerning. Elsewhere, Una Nemo reflects on the insights she's gained into Batman and Robin.