Aliens resurrect dead humans as zombies and vampires to stop humanity from creating the Solaranite (a sort of sun-driven bomb).

Lieutenant John Harper: But one thing's sure. Inspector Clay is dead, murdered, and somebody's responsible.
[first lines]
Criswell: Greetings, my friend. We are all interested in the future, for that is where you and I are going to spend the rest of our lives. And remember my friend, future events such as these will affect you in the future. You are interested in the unknown, the mysterious, the unexplainable. That is why you are here. And now, for the first time, we are bringing to you the full story of what happened on that fateful day. We are bringing you all the evidence, based only on the secret testimony of the miserable souls who survived this terrifying ordeal. The incidents, the places. My friend, we cannot keep this a secret any longer. Let us punish the guilty. Let us reward the innocent. My friend, can your heart stand the shocking facts about grave robbers from outer space?
Gravedigger: You hear anything?
Gravedigger: Thought I did.
Gravedigger: Don't like hearing noises, especially when there ain't supposed to be any.
Gravedigger: Yeah, kinda spooky-like.
Gravedigger: Maybe we're getting old.
Gravedigger: Well, whatever it is, it's gone now.
Gravedigger: That's the best thing for us too, gone.
Gravedigger: Yeah, let's go.
Criswell: Perhaps, on your way home, someone will pass you in the dark, and you will never know it... for they will be from outer space.
The Ruler: Plan 9? Ah, yes. Plan 9 deals with the resurrection of the dead. Long distance electrodes shot into the pineal and pituitary gland of the recently dead.
Jeff Trent: You promise you'll lock the doors immediately?
Paula Trent: I promise. Besides, I'll be in bed before a half hour's gone... with your pillow beside me.
Jeff Trent: My pillow?
Paula Trent: Well, I have to have something to keep me company while you're away. Sometimes in the night, when it does get a little lonely, I reach over and touch it. Then it doesn't seem so lonely anymore.
Colonel Tom Edwards: You speak of Solaranite. But just what is it?
Eros: Take a can of your gasoline. Say this can of gasoline is the sun. Now, you spread a thin line of it to a ball, representing the earth. Now, the gasoline represents the sunlight, the sun particles. Here we saturate the ball with the gasoline, the sunlight. Then we put a flame to the ball. The flame will speedily travel around the earth, back along the line of gasoline to the can, or the sun itself. It will explode this source and spread to every place that gasoline, our sunlight, touches. Explode the sunlight here, gentlemen, you explode the universe. Explode the sunlight here and a chain reaction will occur direct to the sun itself and to all the planets that sunlight touches, to every planet in the universe. This is why you must be stopped. This is why any means must be used to stop you. In a friendly manner or as (it seems) you want it.
Lieutenant John Harper: He's mad.
Tanna: Mad? Is it mad that you destroy other people to save yourselves? You have done this. Is it mad that one country must destroy another to save themselves? You have also done this. How then is it "mad" that one planet must destroy another who threatens the very existence-...
Eros: [shoves her roughly aside] That's enough.
[to the humans]
Eros: In my land, women are for advancing the race, not for fighting man's battles.
[On what that strange sound was]
Lieutenant John Harper: It was a saucer.
Policeman: A flying saucer?
Lieutenant John Harper: It was a saucer.
Patrolman Larry: A flying saucer? What makes you say that?
Lieutenant John Harper: You remember the noise we heard the other night?
Patrolman Larry: We were knocked to the ground, how could I forget?
Lieutenant John Harper: Exactly, but you're not remembering that sound.
Patrolman Larry: There you're wrong, Lieutenant. I'm with a fact the sound is similar, but what about the blinding light?
Lieutenant John Harper: Well haven't you heard? Many times a saucer hasn't had a glow, or a light of any kind for that matter.
Patrolman Larry: That proves it! What next Lietenant?
Colonel Tom Edwards: ...Why, a particle of sunlight can't even be seen or measured.
Eros: Can you see or measure an atom? Yet you can *explode* one. A ray of sunlight is made up of *many* atoms!
Jeff Trent: So what if we *do* develop this Solanite bomb? We'd be even a stronger nation than now.
Eros: [with disgust] Stronger. You see? You see? Your stupid minds! Stupid! Stupid!
Jeff Trent: That's all I'm taking from you!
[pistol-whips Eros upside the head]
Patrolman Larry: Well, that's why you're a detective, Lieutenant, and I'm still a uniformed officer.
Air Force Captain: Visits? That would indicate visitors.
Criswell: [narrating] ... The grief from his wife's death became greater and greater agony. The home they had so long shared became a tomb, a sweet memory of her joyous living. The sky to which he had once looked was now only a covering for her dead body. The ever-beautiful flowers she had planted with her own hands became nothing more than the lost roses of her cheeks. Confused by his great loss, the old man left that home... never to return again!
[brakes screech and the old man screams]
Criswell: [narrating] At the funeral of the old man, unknown to his mourners, his DEAD WIFE was watching!
Colonel Tom Edwards: For a time we tried to contact them by radio but no response. Then they attacked a town, a small town I'll admit, but never the less a town of people, people who died."
Paula Trent: ...A flying saucer? You mean the kind from up there?
Jeff Trent: Yeah, either that or its counterpart.
Colonel Tom Edwards: Why is it so important that you want to contact the governments of our earth?
Eros: Because of death. Because all you of Earth are idiots.
Jeff Trent: Now you just hold on, Buster.
Eros: No, you hold on. First was your firecracker, a harmless explosive. Then your hand grenade: you began to kill your own people, a few at a time. Then the bomb. Then a larger bomb: many people are killed at one time. Then your scientists stumbled upon the atom bomb, split the atom. Then the hydrogen bomb, where you actually explode the air itself. Now you can arrange the total destruction of the entire universe served by our sun: The only explosion left is the Solaranite.
Colonel Tom Edwards: Why, there's no such thing.
Jeff Trent: I'm muzzled by army brass!
Paula Trent: Now, don't you worry. The saucers are up there. The graveyard is out there. But I'll be locked up safely in there.
Colonel Tom Edwards: This is the most fantastic story I've ever heard.
Jeff Trent: And every word of it's true, too.
Colonel Tom Edwards: That's the fantastic part of it.
Eros: You know, it's an interesting think when you consider... the Earth people, who can think, are so frightened by those who cannot: the dead. Well... our ship should be regenerated. We better get started.
Jeff Trent: You fiend.
Eros: I, a fiend? I am a soldier of our planet. I, a fiend? We did not come here as enemies.
Tanna: What do you think will be the next obstacle the Earth people will put in our way?
Eros: Well, as long as they can think - we'll have our problems.
Lieutenant John Harper: Kelton, Get down there and check it out?
Patrolman Kelton: Well, how do I do that sir?
Lieutenant John Harper: By going down there and checking it out!
Patrolman Kelton: Aww, why do I always get the spook details?
Criswell: My friend, you have seen this incident, based on sworn testimony. Can you prove that it didn't happen?
Paula Trent: Now toddle off and fly your flying machine.
Eros: With your ancient, juvenile minds you have developed explosives too fast for your minds to conceive what you are doing. You are on the verge of destroying the entire universe. We are a part of that universe. This is our last...
[cuts off]
Jeff Trent: They here, they're a fact. And the Public oughta know about it!
Inspector Clay: [looking at the two dead gravediggers] Who found 'em?
Patrolman Kelton: The boy and girl over there, Daniel.
Inspector Clay: Medical examiner been around yet?
Patrolman Kelton: Just left. The morgue wagon should be around another minute.
Inspector Clay: You get their statement?
Patrolman Kelton: Yeah, as much as we could. They're pretty scared.
Inspector Clay: Finding dead men like this ought make anyone frighented.
[to Lt. Harper]
Inspector Clay: Have Kelton take the boy and girl back to town. You take charge.
Lieutenant John Harper: Okay, Inspector. What are you going to do?
Inspector Clay: Look around a little.
Lieutenant John Harper: It's pretty dark out there. Once you get beyond the range of those lights, you woun't be able to see your hand in front of your face.
Inspector Clay: I'll get a flashlight from one of the patrol cars.
Lieutenant John Harper: All right, but be careful out there.
Inspector Clay: I'm a big boy now, Johnny.
Eros: You do not need guns.
Jeff Trent: Maybe we think we do.
Criswell: [narrating] ... All of us on this earth know that there is a time to live, and that there is a time to die. Yet death is always a shock to those left behind. It is even more of a shock when Death, the Proud Brother, comes suddenly without warning. Just at sundown, a small group gathered in silent prayer, around the newly-opened grave of the beloved wife of an elderly man. Sundown of the day; yet also the sundown of the old man's heart, for the shadows of grief clouded his very reason... The funeral over, the saddened group left the graveside. It was when the gravediggers started their task that strange things began to take place.
Paula Trent: I've never seen you in this mood before.
Jeff Trent: I guess that's because I've never been in this mood before.
General Roberts: [the General is explaining why a transmission from the aliens has been cut short] "Thats the end of that one. Atmospheric conditions in outer space often interfere with transmitting"
Jeff Trent: Ah, what's the use of makin' a fuss. Last night I saw a flyin' object that couldn't a possibly been from this planet, but I can't talk about it. I'm muzzled by Army Brass. I can't even admit I saw the thing!
[last lines]
Criswell: My friend, you have seen this incident based on sworn testimony. Can you prove that it didn't happen? Perhaps on your way home someone will pass you in the dark, and you will never know it, for they will be from outer space. Many scientists believe that another world is watching us at this moment. We once laughed at the horseless carriage, the aeroplane, the telephone, the electric light, vitamins, radio, and even television. And now some of us laugh at outer space. God help us in the future.
Lieutenant John Harper: Modern women.
Colonel Tom Edwards: They've been like that all down through the ages. Especially in a spot like this.
Lieutenant John Harper: I'll bet my badge that we haven't seen the last of those weirdies.
Tanna: Eros, do we *have* to kill them?
Eros: Yes.
Tanna: It seems such a waste.
Eros: Well, wouldn't it be better to kill a few now than, with their meddling, permit them to destroy the entire universe?
Tanna: You're always right, Eros.
Eros: Of course. But those are not my words; those are the words of the Ruler.
Eros: It's because of men like you that all must be destroyed.
Patrolman Kelton: ...From all I've seen tonight, guns won't do any good. Clay's dead, and we buried him. How are we gonna kill someone who's already dead? *Dead*! And yet there he stands!
Paula Trent: What friends?
The Ruler: Eros. The Earth people are getting closer to that which we fear. Since they will not listen or respect our existence, they cannot help but believe our powers when they see their own dead walking around again, brought about by our advancement in such things. As soon as you have enough of the dead recruits, march them on the capitals of the Earth; let nothing stand in your way. Their own dead will be used to make them accept our existence and believe in that fact.
Patrolman Larry: Strange. If someone had broken in, the dirt should be piled up here somewhere. It looks like it's fallen in, into the grave.
Lieutenant John Harper: Larry, you'll be out of that uniform before you know it.