1941, Chumphon Province. Mok and his ragtag group of young soldiers are thrown against the invading Japanese forces. But the invaders bring with them a terrifying biological weapon. Mek, Mok’s older brother, is an NCO serving close by. Mek is ordered to join forces with the Japanese when they lose control of their weapon, but finds out that his orders could mean the death of his own brother. Operation Undead is set in Southern Thailand during the little known invasion by Japanese troops in WW2. Mek is a corporal in Thailand’s army, a straight arrow, a firm believer in duty and love of army and country, ready to sacrifice himself to save the nation. Mok is the younger brother, cynical beyond his years, a born trouble maker, ringleader of his gang, ready to question every order given, who’d rather desert than fight a war. When a crazed Japanese soldier bites and infects Mok and his fellow conscripts, they find themselves struggling with the violent urges but incredible powers the infection gives them, even as they unwittingly unleash bloodshed around them. When Mek is ordered to join a mysterious Japanese unit led by Dr. Kaito and to hunt down the infected, he realises Mok is on the target list. But then Mek himself is infected, and the two brothers become opponents as they fight for the control of the group and the choices they must make to survive even as Kaito’s bunch of killers close in on their hideout.