Lt. Danner is a fighter in the 2nd Mass. He was a career Lt. in the Army before the attack. He was in the 10th Mountain Division in the US Army. He saw duty in tours in Iraq and Afghanistan. He was also one of the "lucky ones" on leave when the attack came. He served as a courier between Porter and the 2nd Mass. He delivered the pictures to Porter and was at the 2nd Mass when Weaver chose to continue the original plan, even though Porter's last orders were to abort the mission and save as many lives as they could. As the 2nd Mass could be the only ones fighting, after Tom realized that Weaver was wrong and tried to talk him out of it, Danner was ordered by Weaver to lock Tom in the boiler room.
Seeing as Lt. Danners could not be reasoned with, the Half Mass devised a plan that consisted of Jimmy walking down to the cell to give Tom food, only to drop it and cause a distraction, thus allowing Tom to escape. After a brief altercation between Lt. Danners and Tom, Tom ultimately wins, ties Lt. Danners up, and puts tape on his mouth. (Mutiny)
Lt. Danners was discovered shortly after this by Weaver. A stand off directly followed between Weaver, Pope and several members of the 2nd Mass. (Mutiny)