No actual storyline has ever been released for this movie, though in Scream 4 we learn that Stab 5 used time travel as a plot device!
The fan-created DVD case makes up a good backstory!
Ghostface goes back in time to eliminate the bloodline of Ashley Prescott, his victim that got away in Stab 4: Knife of Doom. What ensues is a chilling game of cat and mouse as the maniacal killer ends up in the year 1865 where he has only one goal; Find and terminate Mary-Anne Prescott, Ashley's Great-Great-Great Grandmother.
Based on the best selling crime novel of the same name by former reporter Gale Weathers-Riley.