THE LIVING DEAD AT THE MANCHESTER MORGUE
(1974)

It turns out this experimental machine that uses ultrasonic radiation to destroy insects has another, unexpected side effect: It raises the dead! George and a lady named Edna are caught up in the middle of the rising, at first suspected of the murders themselves and soon becoming the only ones who can save the entire township of Manchester, England.

This is a great movie, very underrated, and one of the first to really exploit what Romero did with Night of the Living Dead. The zombies here seem fairly intelligent and work together, using tools and whatever it takes to kill and eat the living. There's plenty of red stuff and lots of action (the sequence in the basement of a cemetery is worth the watch alone).

Highly recommended!