Note the comma (between Island and Earth).  Sometimes it’s there, sometimes not.  The comma pointedly appears in the original poster art from 1955:

And yet, somebody decided to omit it on the 1964 re-issue posters.  Maybe some studio bigwig thought it was too arty and confusing for movie goers back in the day, go figure:

No matter, the film today remains a classic of 1950s Science Fiction with plenty of weirdness.  A big budget affair from Universal Studios with lavish special effects all in beautiful Technicolor, and probably overshadowed by MGM’s production Forbidden Planet which came along about 9 months later.

Earths best scientists are (unknowingly) recruited by (they later find out) aliens from the planet Metaluna, which is dying and (they later find out) under attack from the Zagons (never explained).  The scientists, at first, don’t notice that the Metalunans look sort of  like earthlings, except they have rather high and bumpy foreheads with unusual gray hair.  Anyhow, 2 of the scientists are kidnapped by the Metalunan named Exeter, and taken to Metaluna, where they witness “The Supreme Excitement of Our Time” (according to the films advertising campaign).  Turns out, the Metalunans intend to bail out on Metaluna, and relocate to Earth and subjugate our free will.  Thankfully, however, the plan doesn’t come to fruition as Exeter bravely saves the earth scientists (just before the Zagons destroy Metaluna) and returns them to Earth (which is none the wiser).  Kinda makes you wonder about our place in the Universe:  This Island, (pause) Earth.  I think I prefer the comma!