Major Crimes Season 4 Episode 18 revolves around the murder of college professor Jeff Ashby. Ashby taught Media Studies, specifically film. At first it appears to be a school shooting, but video footage on the professor's computer shows he was shot in the back of the head as he watched student footage of murdering a woman.

The woman in the film turns out to be Lisa Green, a Hollywood literary manager turned real estate agent. Provenza thinks Lisa and Ashby were having an affair, but Lisa's husband doesn't recognize Ashby nor does he recognize a photo of the shooter. In the meantime, the unhinged shooter is filming commentary on his crimes and has tied up and gagged his brother, Ryan.

Ryan's ex-wife Sarah comes to the station. She says Ryan is a liar but the one true thing he told her is that he has nothing to do with his brother, Brad. The cops use the GPS tracker in Sarah's car to find Brad and Ryan. However, while Brad is in the gas station filling up a gas canister, Ryan drives away despite being tied up and the cops find him. Brad angrily returns home where he has an evil plan involving Sarah.

While the cops race against time to rescue Sarah and apprehend Brad, Rusty has troubles of his own. After Slider is given the death penalty by the jury, Rusty and Gus make tenative plans -- but is Rusty ready for a relationship?

To find out what happens, watch Major Crimes Season 4 Episode 18 online.