John's wife collapses and then dies in the hospital, despite the movie never telling me what's wrong with her. I suppose I'm left to guess...
-Everything Wrong With John Wick In 12 Minutes Or Less
The entire revenge story of John Wick 1 is set into motion by the death of John Wick's wife Helen, who we see collapsing onto the ground by the waterfront before passing away in a hospital bed.
How did John Wick's wife die? Is the cause of death ever mentioned?