Packages with disturbing contents are sent to six people across Washington DC. Simmons and Kristy struggle to connect with David.
In the aftermath of the dam break, massive mudslides wreak havoc throughout Los Angeles; Athena fights to save herself and an agoraphobic woman after her house collapses; a group of pregnant women trapped in a submerged house.
NCIS dives into the competitive world of food trucks after finding a man frozen to death in the back of one.
Sam reflects on his relationship with his father while investigating the complicated case of a killer who is targeting Marines.
Spencer makes a huge sacrifice in order to protect Toby; Aria leaves a message for Ezra; Caleb hacks into "A's" phone and finds an incriminating video.