After the tragic death of Sue Debny, the wife of the Elongated Man, the members of the Justice League of America and most of the DC superheroes are brought together to investigate. Sues murder is unsettling for a couple of reasons: she was a friend, and whoever committed the crime knew enough personal information to be able to sneak past security. Even more troubling are the letters that the family members of other heroes receive, indicating that they are the next targets. The superheroes split into teams to follow the leads that they are most suited to solve.