The Day of the Triffids Meets The US Navy - Operation Deep Freeze, a US scientific expedition to Antarctica, discovers some unusual tree specimens. When the specimens are shipped out for further study, the trees are accidentally introduced to a south seas Navy base, soon revealing themselves to be killer, all-devouring acid-secreting monsters that live by night. The United States Navy is called to action to battle groves of walking trees which bleed acid and seem intent on cremating the entire human race.