A group of college kids are messing around with an old book of spells in a graveyard (as you do) and find themselves projected into another realm. However, upon their return, they discover they are being stalked and dragged back into this alternate dimension one at a time.
Manny The Angel alerts John to these goings on by sending him to help his old friend Ritchie Simpson (a wonderfully nervous and soft-spoken performance by Jeremy Davies), who happens to be the college professor running the class that all four students are taking.
We met Ritchie back in the first episode of Constantine and it's great to see the show revisiting its supporting cast (those that survive anyway), as it helps create the show's world.
Eventually John and Ritchie have to confront the psychopathic occultist Jacob Shaw (Lost's William Mapother) who created the realm that the students are being taken to.
A Whole World Out There is the strongest episode of Constantine to date by a country mile. It certainly helps that he's flying solo initially - with no Zed or Chas to hog the limelight - but the story has that grubby and magical feel of a Hellblazer comic, while echoing horror movie franchises like Hellraiser and Nightmare On Elm Street.
A strong supporting performance by guest star Jeremy Davies certainly doesn't hurt either and thankfully the script by Davita Scarlett and Sneha Koorse only makes cursory references to my two bugbears of the show (the 'scrying map' and the nebulous Big Bad 'The Rising Darkness').
With only a couple of episodes left in this first season, Constantine is finally finding its feet. On the strength of this episode alone, I hope that's not too late to save it from cancellation.