During the Vietnam War [1959-1975] a special US combat unit is sent out to hunt and kill the Viet Cong soldiers in a man-to-man combat in the endless tunnels underneath the jungle of Vietnam. Suicide squads of a special kind.

The Brookedale Psychiatric Hospital is a crumbling institution which barely has enough money to remain open. Formerly a prison, it sits atop a warren of tunnels and sewage system viaducts. But Brookdale has a secret – a secret known by only one person. There’s something living in the tunnels – something that’s developed a taste for human blood…