Real movie summary: A U-boat with WW2 Nazi soldiers, killed and brought back to life to fight as "un-killable", is ship-wrecked on a Caribbean island. 30 yrs later, a "hire-boat" is also shipwrecked there. The Nazi commander of the unit, Cushing, is the only "survivor" on the island. BUT, the "Zombie un-killables" come back to do what they were experimentally used to do in battle ... kill without thought or feeling... uncontrollably... The movie has numerous images that stay with you long after the movie is over, and a musical background in the beginning which was very haunting. Good acting, a believable script, and nice film shooting, round it out to make it a memorable classic. I've had a really tough time locating the film at any video store. Good luck finding it!