Motive to Kill

There's been a mass shooting with over 23 casualties in Atlanta.
FBI agent Blake Wilder and her team are called by D.C. Headquarters to spearhead the case.
Upon their arrival to the crime scene, they are greeted with hostility by the field officers present.
Unfazed by the tension, Blake begins to sort through the identities of many victims, most of them high profiled lawyers.
While attempting to identify a motive, the team sorts through the deceased lawyers' case files.

Soon after, Blake realizes that the footage and evidence regarding this case has gone missing.
And this case now leads to a dead end.

All is seemingly hopeless until a crucial lead points to one undeniable truth.