Maria Brunner was a lieutenant in the German army and a part of the elite KSK. She was the first woman to join the special forces. Born in Dusseldorf in the mid-1980's she saw the reemergence of Germany as a powerful nation in Europe. Like most Germans, she wanted this time for German power to be put into peaceful purposes. She had heard stories from her grandfather of the last terrifying days of World War II when he had served in a Hitler Youth unit in Berlin. He told her, that the people had been seduced by a madman, and lead to their own willful slaughter. Never again he told Maria would Germany destroy itself, and take the world with it. He gave Maria his old Walter P-38 sidearm, and asked to promise him to restore Germany's credibility with the world. Taking her grandfather's promise to heart Brunner entered the Officer's training school. She made through her training by her sheer will and determination. Her skills of weaponry and leadership were recognized by Army Headquarters who requested the young officer join KSK, which Brunner did. There she met Major Paul Lietner, her superior.
Brunner was part of the second Ultranationalist uprising in Russia, and played a key role. Brunner was inserted into Minsk when that city was attacked by Ultranationalist troops. In fierce street fighting Brunner was able to take out strategic command posts, and find intelligence to the Ultranationalist leader Totavich's next move. Flown into Volgograd in order to hunt down Totavich, her helicopter was shot down over the Volga River, and Brunner had to swim across under heavy fire. She and the rest of the team fought their way up Maymev Kurgan, serving as the main Ultranationalist headquarters. Pinned down, she was separated with Leitner from the rest of the team which was linking up with British SAS and American Marines. Knocked out by a grenade, she was captured. It was here she found out her best friend Leitner was working with Totavich. Totavich had her nearly executed, by she was rescued by British and American troops who had found the German team. Back in Germany, she requested to continue the hunt despite her trauma while captured. She lead the new international team comprising of British SAS under the command of Soap MacTavish, American Marines under Eric Taylor, and her own KSK team. The intel gathered suggested that Totavich was transporting a nuclear missile by train. The team intercepted the locamotive, and fended off vicious Ultranationalist counterattacks. After dealing with the train, the Brunner rescues cutoff Israeli commandos also hunting Totavich. Their leader Sgt. Moshe David, was surprised to be rescued by a German soldier. With the Israeli commandos now helping her team Brunner assaults a missile boat transporting another nuclear missile, attacked by the enemy Brunner called down airstrikes to delay the enemy, and the team escapes the boat before it sank. Brunner attacked the main ultranationalist army in Perm. Brunner snipes enemy positions but if spotted by a Mi-24. David sacrifices his own life to save Brunner from the Helicopter. Before he dies, David tells Brunner how proud he is as a Jew to serve alongside a German soldier. His words trouble Maria, who remember what her grandfather told her and is comforted by Sgt. Taylor whom she falls in love with. After attacked enemy forces in Yekaterinburg, Brunner and the team finally reaches Totavich's Ural Mountain base. Totavich in desperation launches a missile. Fighting frantically in the base, the team aborts the launched missile, but the controls for one ready to be launched are locked. Brunner goes after Totavich herself knowing he has the codes. Alone she kills most of the Russian's men, but is wounded by Leitner. She kills them with her only remaining weapon, her grandfather's P-38. Taylor arrives to kill the rest of the guards and places C4 charges on the Missile. Brunner and Taylor escape before the base explodes.
For her efforts against the Ultranationalists Brunner was awarded the Cross of Honor for Bravery. After the ceremony she leaves with Taylor and MacTavish to a biergarten to sit down and relax.