The start of his run introduces Angie Spatchcock , a fellow magician , and reintroduces his niece , Gemma Constantine , who have also fallen into magic use , to her uncle 's consternation . After ridding his sister 's house of an evil spirit , and finding out Gemma have gone missing , John return to London , to find his old colleagues and enemies are all taking sides in the hunt for a mythical item , known as the Red Sepulchre . John eventually locate the item , and find Gemma , freeing her from his old enemy Josh Wright . Following several forewarnings , Constantine then travel the world to set up a plan for a forthcoming tragedy , which will occur when " Three doors are opened " , involving Swamp Thing and the Garden of Eden amongst others .