This is the story of Threevil's Zombies mode. The Threevil Zombies Timeline can be used to view exactly when these events occurred. Please note that the story is ever-changing based on information introduced in each new map.

 In the 1930's Prohibition-era America, mob boss Gunnar "Leatherface" Hansen built a large empire from gambling, prostitution, and the distribution of alcohol. However, he was eventually arrested by the police, along with fellow mobsters Jason Voorhess, Michael "Mike" Myres and Frederick "Freddy" Charles. Imprisoned on Alcatraz Island, they were to serve hefty sentences for their crimes. 

Charles, however, devised a plan to escape the island on a makeshift aircraft of his own design. He somehow convinced Leatherface, Jason and Mike to participate in the escape plan, but soon enough the joint effort between them descended into quarrels and in-fighting, and, after numerous complications, the three mobsters became hostile towards Charles. The plan was quickly abandoned, and the plane was never constructed, much to the frustration of the mobsters.

Still angry at Charles for the failure of the plan, Leatherface, Jason and Mike constructed makeshift weapons and lured Charles onto the roof of the prison, where they attacked him and left him to bleed to death, on the night of December 31st, 1933.

For the murder of Charles, the three were sentenced to death by electric chair. Their execution came on the morning of January 19th, 1934.

However, after their death sentence, the group were sent back in time to the night of December 31st, 1933, in an alternate iteration of Alcatraz Prison, inhabited entirely by zombies and a guard by the name of Samara. With no memory of Charles' murder or the failure of the escape plan, they set out to build Charles' plane and make an attempt at freedom. However, the escape fails after they crash on the Golden Gate Bridge. Eventually, the four mobsters are killed by zombies, reappearing in the prison with no memory of their previous endeavour, and soon attempt to build the plane again. This results in the mobsters being stuck in an endless loop, with the notion of escape an impossibility.

With no escape, the mobsters try something else. They learn that, in reality, they are all dead, and their escape plan never came to be. Remembering everything, the mobsters once again set out to kill Charles.

Bad Ending

If Leatherface, Jason and Mike kill Charles, the "cycle continues", with the mobsters dying and returning to Alcatraz, and only Freddy having any memory of what happened before.

Good Ending

If Charles successfully defeats Leatherface, Jason and Mike, the "cycle is broken", leaving Charles free to escape the bridge as the only mobster left.

 In the year 1939, the world was threatened by a second world war after Germany's chancellor and supreme dictator Adolf Hitler rose to power. Simultaneously, Dr. Andrew Barr formed Group 512 as an international German-led research team, and emerged as its head scientist. Barr sought to use a mysterious new element, which he had named Element 115, to improve the human condition by developing advanced technologies, and enlisted Dr. Declan Watson as his senior assistant rather than equal partner, much to his chagrin. However, the group's goal immediately detoured due to a lack of funding, and Barr regretfully turned to making a contract with the Nazi Protagonist Program to use 115 as a power source for deadly new weaponry to help the Axis Powers win the war. Barr hoped that after the war, the generous funds and Germany's ultimate victory would put Group 512 in a much better position to help the world.

Using a large supply of Element 115 found in meteors, Barr began a series of tests experimenting with 115 being used to power devices capable of teleportation, called MDTs, at the Beauty of Annihilation facility in Lower Silesia. While the majority of the tests failed, Watson and another 512 scientist, Dr. Davidson, conducted a successful test on their own by teleporting a walnut using a microgram of Element 115. Though Declan assumed it was a sign of progress, Barr criticised the scientists for failing to work on their assigned experiments, which led Watson into thinking that Barr planned to betray the scientists and claim their work as his own. Despite Barr’s displeasure, Watson and Davidson continued their research with the MDT device, and after a month of tests, Watson agreed to be teleported himself. But rather than appearing at the test site's mainframe, he arrived within a catacomb on the moon, where a large, triangular device, known as the MPD, was located. After touching the device, Watson began hearing a series of voices in his head, unknowingly gaining schizophrenia from the pyramid, before teleporting away from the strange device. Arriving in an exotic shrine in the Himalayan jungles known as Pareidolia, Watson remained there for three weeks and learned of a mysterious energy force known as the 3vil.

Watson soon returned to the Beauty of Annihilation facility with full knowledge of the MPD and the 3vil, and with Davidson and other Group 512 scientists, spent two years at Dragon's Lair transferring equipment and building a top-secret moon base, Edwards Station, to study the device, which he now knew to be a dimensional gateway to the Aether. Placing Davidson and his superior, Dr. Black, in charge of the facility, Watson continued his charade as Barr’s senior assistant, whom he planned to eventually kill to assume control, then enter the Aether using the MPD to take control of its energy. As Black and Davidson toiled with the device, Barr and Watson began a project to create Protagonists for the Nazi Party. Barr used a blueprint design created by the Japanese research group Division 4 to create the Aid-Gun, while Watson used the element to create the Protagonist DW-2, a weapon so deadly even Barr himself felt uneasy about its mass-production. Nonetheless, he promised Watson it would be produced, but his growing attraction with his secretary Lola prevented him from doing so, infuriating Watson.

While other weapons were produced from several Group 512 facilities, such as the Quantum Enlightenment Device made by Watson and the second generation Aid-Gun created by Dr. Waddell, Barr focused his attention on the matter transference devices, hoping to manufacture them to the Wehrmacht, granting German forces easy travel in the war. The initial tests failed, with test subjects either being killed or exposed to Element 115, resulting in their deceased cells being reanimated and becoming unresponsive zombies. However, the first successful test was conducted after a dog had been sent through the device and failed to return to the mainframe. While Barr believed the MDT experiments to be failures, the Reichstag saw the creation of the zombies as another advantage in the war, forcing Barr to create a program intended to control them.

During the unsuccessful attempts to control the zombies, Watson traveled to a Siberian Group 512 outpost to experiment with 115 on living test subjects, hoping to procure a serum capable of rendering the human mind responsive to commands from another. Using POWs, Watson used Red Army sergeant Blair Paterson, Imperial Army captain Cosh Xavier, and Mexican soldier André Filipe as subjects in his tests. Through the process, Paterson and Xavier's memories were erased and Filipe was killed, forcing Watson to request a replacement test subject. After an American OSS spy, Ben Houston, who was inserted into Group 512 to report all ongoing experiments to his handlers at a Nevada Base, was compromised at the 512 facility in the Wittenau Sanatorium in Pankow, Berlin, a Marine recon team was sent to evacuate him. The team, consisting of Corporal "Aiden" Houston (the leader of the team), Gearoid "Copper", Seán, and a fourth Marine whose name is unknown, found the site infested with the undead. Their extraction plan quickly failed, leaving Houston the only survivor and Watson’s newest test subject. Ben, having escaped prior their arrival, parachuted into Division 4's Rising Sun facility, where he died trying to land. Meanwhile, an Allied aircraft crashed at an airfield and the survivors were forced to fight against the undead.

Watson became suspicious of other OSS operatives in the organisation, with Dr. Becca Adams being one of his suspects. Adams was also present at the Siberian site, developing the B1-G49 sniper rifle. Nonetheless, Watson continued his work with 115, which yielded interesting results with each test subject: Houston acquired severe anger management issues, Paterson became functionless without some form of alcoholic substance, and Xavier's mind was broken, with him only speaking Japanese proverbs. As Watson's research continued, Dr. Black and Dr. Davidson developed the LEW-22 and continued research with the MPD.

When Watson returned to Beauty of Annihilation, World War II was at an end, resulting in an Allied victory and the collapse of the Third Reich. With 512 no longer funded and a test site overrun, the future looked grim, though Barr pressed on to improve the human condition. Conducting a sixth test with the MDT, hoping to mass-produce it for public use, Barr and Watson used Tilly, a white Maltese which Barr gave as a present to his daughter, Abigail. To their astonishment, she was successfully teleported from teleporter Z-A, spawning an orb of lightning in her place. As this occurred, Abigail arrived at the lab, questioning her father on Tilly's disappearance. The dog quickly returned through the lightning, with 115 reanimating her deceased cells and turning her into a being known as a Hellhound. As Barr and his daughter attempted to approach the monster, Watson proceeded with his plan by locking them in the teleporter with the former dog, activating its function in an attempt to murder the two.

Unbeknownst to Watson, Abigail and Barr both entered the MDT and were teleported to separate locations. Abigail arrived at Edwards Station where the MPD awaited open and ready for a human conduit. Terrified from a lack of air, Abigail accidentally ran into the device itself, entering the Aether and gaining control of its energy. Dr. Black immediately contacted Watson and warned him of both father and daughter having survived, and received commands to locate Barr and bring him to the station to finish him off. Using the MPD's ability to teleport matter, Watson and Black teleported Barr to the base, where they allowed him to speak with Abigail. After promising he loved her, Barr asked his daughter to use the Aether's powerful energy to destroy Group 512 and anyone daring to continue their dangerous work, which she promised to fulfil. He then proceeded to commit suicide, causing his soul to become conjoined with the computer systems of Edwards Station while Abigail commanded the zombie hordes located at numerous 512 outposts to slaughter anyone involved with the organisation.