Back Part 2 follows the modern-day trekkers into the Laotian jungle as they travel to the Ho Chi Minh Trail in the tri-border area of Laos, Vietnam and Cambodia, looking for what Mark's grandfather, Spike, left behind on his 1968 Special Forces mission.

They have to deal with psychological, natural, historical and Vietnam War-related problems which unexpectedly arise as they penetrate deeper into the jungle, including wild animals, booby traps and unexploded ordnance, as well as far greater dangers under the triple canopy. Spike's 1968 mission also has unfortunate repercussions for them.

They are put at risk by the actions of their fellow-travelers and end up being hunted through the jungle, imprisoned and tortured and they need to find a way out, when Brad's Marine Corps training kicks in.

But can he save them in time?