During the Outbreak of the Rage Virus in the United Kingdom, Mitchell was among the soldiers sent to cover the Forty-Second Blockade protecting Manhester, defending it against repeated attacks. However, The Infected eventually overran the blockade and entered the city, killing all the soldiers at the blockade except for nine, including Mitchell.
Mitchell and the other surviving men, led by Major Henry West fled to the Worsley House in the forest, which they fortified against attack with mines, tripwires, barbed wire and barricades. On Day 23 of the outbreak, Major West made a promise to his men that any female survivors they found would be forced into sexual slavery. When Mailer was infected 29 days into the outbreak, Mitchell knocked him out and Mailer was chained up.
28 Days Later
31 days into the outbreak, Mitchell and several of the other soldiers drove the Manchester Three to the Worsley House after the three survivors were found at the blockade. The trio were then taken in by Major West.
The following night, at dinner with the survivors, Mitchell mocked Bell for believing that things would eventually return to normal. The Worsley House was then attacked by the Infected, but Mitchell and the other soldiers fended them off; Mitchell by mowing them down with a machine gun. Afterwards, Mitchell mocked and attempted to force himself on Selena. When Jim intervened, Mitchell pinned the former to the floor before Farrell violently forced Mitchell to release Jim by punching him in the face. Mitchell shortly after attacked and beat up Farrell with the other soldiers when the latter tried to help Jim, Hannah and Selena escape.
The next day, Jones and Mitchell took Jim and Farrell out to a body dump in the woods behind the Worsley House to be executed. Mitchell wanted to kill the two by skewering them with a bayonet, much to Jones' horror, and when Jones shot Farrell (the shot passing in close proximity to Mitchell, hurting his ear) to spare Farrell a slower death by Mitchell, a vicious argument ensued between Jones and Mitchell, which gave Jim time to escape. Mitchell and Jones searched for Jim, but gave up and left him to die out in the Infected-filled woods after discovered he had escaped outside the perimeter.
That night, when the recently-released Mailer rampaged through the house, Mitchell sent Bedford to kill Mailer, while he forcefully took Selena upstairs. When Mitchell and Selena heard Jim break into the mansion, Mitchell locked himself and Selena in a room. With the two temporarily safe from the rampaging Infected, Mitchell began making vulgar taunts to Selena, when Jim came in through the ceiling and took Mitchell by surprise, bashing his head against the wall repeatedly in a fit of rage. Jim then gouged Mitchell's eyes out by pressing his thumbs into Mitchell's eye sockets, slowly killing him while he screams in horror and agony. Also causing Selena to believe Jim was infected.
Corporal Mitchell was very vulgar, sarcastic and insensitive. He also took pleasure in the suffering of others - and made vulgar, cocky, sarcastic remarks to others. He also appeared to be the most vicious and least stable of West's men - but it is not known if his evil streak developed before or during the outbreak.
Although he is pure evil and sadistic, there is one person Mitchell actually seems to have any respect for: Major West.