Grace gets a call where someone is at a house holding people hostage.
Carlos shows up. They figure out that someone SWATed them and when Carlos tased them the knife went into him. He dies.
Grace takes a leave of absence because she doesn't feel she can trust herself to make the calls.
Grace goes to Carlos to talk to him about it because they're angry and want to do something about it.
Judd gives them a lead on how to track down who was making the calsl and why.
Owen punches a guy when he's out on a date with Catherine. She gets upset with him for it.
Catherine gets flowers and when she opens the note, a powder hits her in the face. She calls in a biohazard
The Feds show up to take over and find the person who delivered the message.
Tommy and Owen are with Catherine and explain to her what it could be.
They find the kid who delivered the flowers and when they start interviewing him, he collapses and starts bleeding out of his nose and mouth. He's considered a biohazard.
They find out that the powder was actually corn starch
Carlos and Grace find the right person who did the SWATing and track themdown to LA they call in Athena to help find the guy and they do.
Owen and Catherine have their date night at his place. When the head to the bedroom they find a dead pig in Owen's bed with Toxic Pig written on the walls. It's likely done by the same person who sent Catherine the floweres.