In the sweltering jungles of Mindanao, the elite Special Unit 21, led by the resolute 1Lt. Bert Garces and the seasoned MSgt. Martin Barrientos, embarks on a perilous mission to neutralize a band of insurgents led by the enigmatic Kapitan Baltog and his "Alsa Puersa," a splinter group rumored to be operating with unusual ferocity. Their pursuit leads them to the isolated Barangay Pototan, where a local, Bunag, speaks of unsettling occurrences – his father seemingly coerced into joining a silent, growing force of "undead soldiers."