Let's figure this out.

So. Let's figure this movie out.

We see a biker guy stop by the side of a two-lane road and walk off into the darkness. He returns with a dead or unconscious woman slung over his shoulder, who he then proceeds to carry to the back of a van.

So; questions from this initial set up:

Is the woman dead? Why is an attractive woman out there alone? Who is the biker guy? Did another accomplice drive the van? Who is this biker guy and how does he apparently know there is an unconscious or dead woman out there off the road in the darkness? I say unconscious because there is no apparent wound or sign of decomposition.

(given what we receive on film subsequently, any answers to these questions is pure speculation.)

Next scene: weird featureless room with apparent unconscious or dead body of woman who was slung over the shoulder. Unconcious/dead woman is stripped down by a second naked woman.

More questions:

What is going on here? Later in the film we do learn that the second naked woman (Scarlett Johanson) is actually a black humanoid creature of some kind under an apparent fake skin. So why is she stripping down this other apparently human/maybe alien woman? Is this the easiest way for this humanoid creature to acquire clothing? Stripping it off a corpse that was fetched by a motor bike guy? What happens to the corpse/unconscious woman after this scene?

(subsequent scenes do not shed any light on the nature of this scene. Any answer is pure speculation)

After this, we get into the 'meat' of the movie. SJ wanders about in a van, trying to pick up single lonely men, apparently conscious of her feminine wiles. The apparent purpose is to lure the men into a bizarre room; she walks across a black surface, the men follow, but slowly sink.

The first time this happens there is little to suggest what is going on. Later, it is vaguely suggested that the men are turned into a bloody meat goop. However; we do not see SJ actually consume any of this; or see any heightened/lowered activity level to here before or after the 'kills'. She remains somewhat monotone. At one point after sparing a potential victim she tries to eat a piece of cake, which is the strongest suggestion that maybe these men are a source of sustenance to her.

Then there is the scene with the beach murdering. Apparently SJ is also capable of bludgeoning somebody to death with a rock and then dragging their corpse somewhere? This doesn't seem to fit the pattern.

Given the impossibly weird nature of the black floor/goo room, one can only reach the conclusion that the scene is not actually real (SJ does not have an actual physical room constructed somewhere in Scotland that is perfectly black and has a black floor that changes properties when a victim walks over it - how could such a room be hidden in such an otherwise normal setting?); but some sort of allegorical scene.

Which leads one to question, alright, what are we alluding to here in the psyche of the human mind?

Men do like attractive women, yes. Women can be men's destruction. Alright, simple enough. And the death of the victims does eventually have an effect on SJ. She gains sympathy for her prey, so to speak. She tries to reform, letting a victim live, experiments with a semi-normal sexual interaction with a man, tries to eat normal food, but fails. The failed sexual encounter puts her over the edge emotionally and we all knows where it goes from there - getting lost in the woods, attempted rape, discovery, and death via burning (also a pretty weird scene - not sure I would have the balls after attempting to rape a clearly not human demon creature to come back quickly with gasoline and try to burn it). So at least there is a character arc and we do have a standard tragedy.

But I'm not really sure what to make of it. If she is truly alien, why does she experiment sexually? I get the trying alternate food (cake scene), but why the sex? eh, whatever.

FURTHER complications:

More confusing still, it seems that the guys who go into the black goo don't immediately die? They are actually in a state of captivity/semi-consciousness, and can also interact with other previous victims? How does that fit in to any allegory? Is the black goo an actual real physical place rather than just an allegorical thing? What does being trapped under liquid and being able to see a previous victim's penis say about the human psyche? Is this just part of how SJ's black goo room works, it is actually a weird physical room that exists, kind of like a refrigerator for her victims? Surely an apparently alien creature can find easier ways to get meat... but maybe the black humanoid alien doesn't actually eat the meat, it really gets its energy off of male lust followed by fear?

Whatever man.

The biker guy makes more appearances, but it is unclear what his relationship and motivation is. The biker guy is maybe some kind of 'handler' of the black humanoid creature. Maybe he's another alien? Maybe the black humanoid creature is a government experiment? All we have established is that the biker guy appears to live in a normal house and has a nosy old woman neighbor peering at him suspiciously.

Given what we see on screen, the most interesting reviewer take-away I found that I think jives the best is that this is kind of an 'anti-bambi' tale; it warns us not to have sympathy for our victims. If we do and try to reform ourselves, our true nature and society's inability to accept us will lead to our destruction. WHICH IS NOT A VERY GOOD MESSAGE AT ALL. That and something about weakness and superficiality, callousness. eh.

That, and boobs. SJ's boobs. and full frontal.