<p>10:00 a.m.<br>The principal of Opportunity, Alabama's high school finishes her speech, welcoming the entire student body to a new semester and encouraging them to excel and achieve.</p><p>10:02 a.m.<br>The students get up to leave the auditorium for their next class. </p><p>10:03<br>The auditorium doors won't open.</p><p>10:05<br>Someone starts shooting.</p><p>Told over the span of 54 harrowing minutes from four different perspectives, terror reigns as one student's calculated revenge turns into the ultimate game of survival.</p>