Deen participated in a game of capture the flag with the Indian PCs. Deen's role was for him and Averbach to take the cars that Wit O'Toole stole as a distraction so O'Toole and his men could get away. O'Toole thought that Deen and Averbach would be riddled with spider rounds, but Deen and Averbach fought and were not hit by a single shot during the game.
During a training exercise with the Indian PCs, Deen portrayed an extremist protecting a hostage, who was played by Calinga. Wit criticized Deen afterwards for going too easy on the new recruits, so Deen was sent into the jungle for another training exercise, having only had spider round patches to protect him with to simulate spears.
A couple months after training the Indians, Wit O'Toole called all available MOPs in his units to a meeting to discuss being ready for an alien invasion. Deen and others made fun of O'Toole at first, but were convinced that it was necessary to be ready for this possibility.
Wit called Deen and the other MOPs in the unit together to discuss helping in China. Even though helping in China likely meant a court martial, Deen and all of the other MOPs in the unit agreed to go with Wit to fight the Formics that landed in the Southeast. Deen followed Wit's lead to a dry cleaners, where all of the MOPs were refitted with civilian clothing. After all the MOPs separated into groups in order to travel incognito, Deen went with Wit, Calinga, and Lobo to the train station in order to travel to Pakistan.
In China Wit, Calinga, and Mazer Rackham went to destroy the Formic lander with a tactical nuke and self-propelled drill sledges. While they were gone, Deen was put in charge of the remaining MOPs at the unoccupied Chinese base. After the nuke was detontated and none of them returned, Deen and the others searched for information regarding them and the nuclear explosion. Bingwen shared with Deen and the other MOPs that General Sima was holding Wit and Mazer custody. Deen wanted to arrange a mission to save the two, when Bingwen wrote a letter to the world congratulating Sima on his plan to destroy the Formic lander in order to hopefully get Wit and Mazer released. Deen liked Bingwen's plan, and along with Bolshakov helped translate Bingwen's message into proper English.
Wit contacted Deen to tell him and the MOPs to be picked up by the Chinese, so they could be taken to the Dragon's Den. When greeted by Chinese Lieutenant Li, Deen was asked about Bingwen since he was a child. Deen defended Bingwen and Li eventually agreed to allow Bingwen to come to the Dragon's Den. At the Dragon's Den, Deen and the other MOPs were reunited with Wit after he commented on how stubborn Wit was.
Several days later, Bingwen was sent off to military school up north, and Deen went to say goodbye. He joked, saying that Bingwen's uniform would have stars on it in the near future.
Deen went to Luna with the MOPs, where he signed a liability form in order to join the mission to infiltrate the Formic ship. On the Valas, Victor debriefed the MOPs and trained them to work in zero gravity for their mission on the Formic scout ship. Deen ended up being one of the eight MOPs selected to join the mission.
Deen held off the Formics at the back of the group as Wit, Shenzu, Victor Delgado, and Benyawe made their way to a safe shaft. Victor cut Shenzu and Deen a hole into a new shaft, but Deen had been hit in the legs three times by projectiles, immobilizing his legs. Victor fixed the holes in Deen's suit that were punctured, and then made their way to the radiation safe corridor where Mazer was. After Wit had Imala start flying. they realized the plasma gun would not be turned off, killing Imala and ruining the technology, so Wit sacrificed his life to turn off the plasma guns at the helm. While at the helm, Wit needed some motivation to continue on and complete his tasks, so Deen began singing an old Navy song that Wit had taught the MOPs.
Lem Jukes then reported to the team that the Formic landers were closing in on the position of the Fomic scout ship. Deen and the others made a plan to shoot the Formics with the plasma gun and ship debris. Deen went to the surface of the ship in order to guide Victor while he was at the helm firing the weapons and steering the ship. Deen directed Victor as he steered the ship to destroy the two Formic landers, but the second Formic lander released many transports and skimmers before it was destroyed. Several of those landers released Formics on the surface of the ship and overran Deen's position, leading to his death.
- Deen hailed from Great Britain.
- "A little confidence, Captain. Averbach and I don't give up that easy."
- — Earth Unaware, page 137