Olsen's history is largely unknown. He was stationed in the South China Sea with his Marines six months prior on pirate deterrence.
Olsen and his squad were sent on a covert joint US-Chinese mission to the Sino-North Korean border. There, they were tasked with extracting a defector, codenamed Highbeam, who had been the lead programmer of North Korea's nuclear program. CIA agent Kovic was made the acting leader of the mission, much to Olsen's dismay.
A Marine pilot named Tex flew the squad to the meeting point on the North Korean side of the border. Upon landing, Kovic orders Olsen and the other Marines to surround Highbeam's vehicle as he approaches in case something goes wrong. Kovic initially attempts to speak to him through several dialects. When Kovic reaches out to Highbeam, he exits his vehicle, and promptly runs away, screaming at the squad to get away from him. It is soon realized that Highbeam had a bomb strapped to his chest, with the explosion killing Kean and heavily wounding Deacon who eventually succumbs from his wounds.
North Korean forces then ambush the Marines, wounding Faulkner and forcing Kovic to order the Tex to leave them. No sooner then he does Olsen screams over the radio for Tex to return and cover them. As KPA forces are engaging, an argument between Kovic and Olsen breaks out from Olsen defying Kovic's orders by telling Tex to return.
Olsen argues to why Tex was ordered to leave as they would then be unable to be extracted. Kovic retorts that if Tex was shot down, he would not be able to call for help and they truly would be trapped. Olsen then responds angrily, stating the Kovic led them into an ambush and that Kovic can "go fuck himself" as he gets his remaining men out alive. Kovic then lunges at Olsen for his insubordination, only for Olsen to kick him in the crotch and send him in the snow.
It was at this point that Tex returned giving cover fire with his grenade launcher. Olsen then orders Price to help Faulkner to the landing zone, only for the Sea Hawk to crash into the snow and explode for unknown reasons. Despite their fight, Kovic proceeds to cover Olsen, Price, and Faulkner from the ensuing explosion with his body.
They then take cover behind Highbeam's destroyed vehicle, only for Olsen then blames Kovic for the Sea Hawk's destruction which may have resulted in another argument if an enemy sniper hadn't shot and stuck Olsen in the thigh thereafter. Price and Kovic administer first aid as more NK forces arrive in jeeps. Kovic rushes from cover to commandeer one of the jeeps and proceeds to pick up the group.
As Kovic drives them away, NK forces are in pursuit. The ensuing chase causes Kovic to crash the jeep, ejecting everyone. Kovic then recovers from the crash and jumps on the enemy jeep, killing all of its passengers. He picks up the Marines and drives them toward the military border, where the Chinese had agreed to supply support should it be needed and requested. They eventually arrive at the deserted checkpoint where Kovic goes to an old phone to call help.
As Kovic returns to the jeep, he loses his footing from exhaustion and collapses. Kovic later wakes up covered, and somewhat camouflaged, in snow as unidentified men arrive only to discover that Price and Faulkner have seemingly disappeared and that Olsen has died either from freezing or his wounds. Kovic solemnly closes Olsen's eyes as his body is hauled away by the mysterious "helpers".
- Olsen has an extreme dislike for the CIA, explaining his continued hostility to Kovic before his death
- Olsen was constantly undermining Kovic, stating he had better intel and kept questioning his actions.
- He appears to know a secret about Kovic that Garrison told him but was cut off by Kovic before it was revealed.
- Garrison revealed that Olsen had been on his last tour of duty at the time of his death.