It was Oracle who apprehended the supervillian The Calculator when he murdered people in an attempt to cure his comatose daughter Wendy Harris. Seeking revenge of Oracle and determined to get the now awake (but paralyzed) Wendy into his custosy, Calculator began killing people by infecting them with a technology bases plague that brainwashes them and lets Calculator control them or excutes them. Detective Nick Gage was assigned to investigate the murder of the first victim. But while he was in the building investigating the murder, Calculator infected both a female worker and security guard. The brainwashed guard was set to murder Gage, but Steph arrived in time to save Gage with a well paced batarang.Calculator made the guard throw himself out the window, and with a grumbled "this is gonna 'suh-uck..." Steph roped the guard with her batarang to break his fall. However, holding up a guy three times her size put a strain on Steph. Even as Gage came to help her, the Calculator remotely terminated the guards life. Then, the Batrope slipped and the man fell.
Steph tried to throw herself after him, but Gage restrained her. They take the dead guard to Ghoul the coroner, who performed an autopsy and saw the man had the same weird metal in his blood as previous victims. Oracle recognized the technology in the blood as being the same Apokolips tech Calculator stole earlier.
Figuring out who's behind this, Oracle demanded Steph get back to the Batcave. Meanwhile, the Calculator sits with the corpse of his son Marvin and terminates the female worker. He is determined to get revenge on Oracle and get his daughter back.
Oracle turn decided off her computers and maintain radio silence so as not to give Calculator an in. She also warned Steph to watch out, because Calculator might try to get to Oracle through Batgirl.
Calculator set his plan into action. He knew Oracle's face, so he uses a Justifier helmet he took from Apoklolips to help him broadcast a signal for everyone to attack Barbara Gordon.
Barbara is teaching class when Calculator broadcasts his signal. Steph is next to Jordanna Spence when she is affected. Jordanna's eyes glowed red and she made"01010" sounds as she sees Barbara in a faculty portrait. Babs entire class (who have been texting) attacked her, and Babs is forced to defend herself with escrima sticks. Steph arrives to help as Batgirl. Babs explained that the signal must be Calculators.
Steph tried to help Babs get to her car, but they were overwhelmed by a swarm of techno-zombies. Both women fight, but Babs was pulled out of her chair. She yells at Steph to get out of there, but Steph refuses to leave her. The zombies (which include James Gordon!) infected Oracle with nanites, encasing her in a silvery shell. A zombified Huntress, Catwoman and Man-Bat leapt from the rooftops to attack.
After being infected by nanites, Babs hallucinated a dream world where she has an idyllic family with Dick Grayson. However, she saw Steph calling out, trying to rescue her while surrounded by technozombies. This was enough to snap her out of it, but then the Calculator arrived in her hallucination dressed like The Joker had been before he shot her. It turned out Calculator had decided to hack into Babs brain to find out all her secrets before killing her. Babs and the villian battled in Barbara's mind.
Steph managed to defeat and escape all the brainwashed heroes, and she teamed up with Wendy to track down the Calculator back to his base (they both commiserate over their dads being jackasses). Determined to have her mentors back, Steph jumped out of a jet to confront Calculator and rescue Oracle.
This all happened in Batgirl #9
At Calculator's base, Oracle is seen entering a memory from his childhood. In the sequence, a child-Calculator is in a cage, and it becomes apparent that his mother locked him in there and wouldn’t let him out until he solved a choice rubix cube several times. Oracle feels deep pity for the young Calculator until the grown version of him attacks her in the present. Then both he and Oracle are transported to another memory of his; this time of his children’s birth, and the death of his wife. He becomes a distraught wreck, and Oracle is able to escape. She goes looking on one of his many computers for a way to disconnect their minds when she turns around and another one of his past memories is there. This time it is a scene of Calculator beating Kid Eternity, trying to get him to turn into his deceased son Marvin. The present Calculator decides to cancel the entire operation, thus leading to both his and Barbara’s deaths.
Steph arrives and rescues Babs just in time all the while Wendy comes into contact with her father; Calculator and uses his main computer to put him into ‘Standby Mode,’ disabling him for good.