It's the late 1960s. The Vietnam War is intensifying as America begins sending more troops to the front lines. An elaborate underground tunnel system has been discovered to be in use by enemy forces. A select group of U.S. soldiers are sent in to explore them. These men were better known as tunnel rats and Samuel Holt has just enlisted into this specialized group.
After a routine patrol goes haywire, Holt finds himself trapped in the heart of the tunnels. There, he makes an alliance with an unlikely creature and together they journey through the dark, hellish underbelly of the jungle. Will they reach their freedom or will they just be more casualties of war?