Artie's trial before the Regents clears him of charges after Leena dies by his hand, but his own guilt may be the harshest punishment possible. Claudia is deeply worried about him, so when a ping comes up - a man buried alive in a state park in Oregon - Pete takes Claudia in order to clear her mind a little.
Myka stays behind with Jinks to keep an eye on Artie, who's trying to complete the tasks once performed by Leena. He refuses their help sorting new artifacts with a room-sized Feng Shui wheel Leena used to use, but when he shelves his first item, it activates all the others in that aisle, including da Vinci's gargoyle, a hyperactive defense system the flies through the air. Artie must rely on Steve and Myka if the thing is going to be neutralized.
Claudia and Pete discover a strange symbol near the murder site, as well as a cell phone with a message that leads them to a second dead body, killed in the same way, and with the same symbol nearby. Pete looks the symbol up in the NSA database and discovers that it's the logo of an eco-terrorist group called The Last People On Earth. Only one member of the group, Ryan Clayton, was tried for their crimes - blowing things and people up in the name of Mother Earth - and he recently died in Prison. The corpses were also members, and the final member, a woman named Autumn, is the head of a local environmentalist group. They spoke to her earlier, but it looks like she didn't tell them all she knew.
Claudia tracks down Autumn while Pete interviews the plaintiff in the case, a logging magnate. In his office, Pete spots a familiar face - it's the park ranger they interviewed! He rushes to Autumn's house to discover the Ranger holding a glowing lantern and abducting Autumn. Claudia revives from a blow to the head just in time to dig Pete out of a fresh mound of dirt before he suffocates. They race to the logging site and order everyone to evacuate, but they refuse. They spot the ranger - who's actually Evan Clayton, brother of the deceased Ryan, and he's bent on burying the whole logging site and everyone in it.
Claudia zaps him just in time, and in a daring maneuver on the cliff side, she and Pete snag and bag the lantern. Later, when Evan is in custody, Claudia consoles Autumn and finds out that she was the anonymous tipper that lead to Ryan's arrest when he started taking their mission in a violent direction. She, like Claudia with Artie, did what she had to do to protect everyone. Claudia gets one step closer to forgiving herself.
Back at the warehouse, Artie, Steve and Myka have felled the gargoyle with a stunning piece of teamwork and derring-do, and he allows them to help him shelve the artifacts. The Feng Shui wheel was picking up on Artie's sadness, but when the level-headed Jinks enters the wheel, the essence of the artifact comes forward as "indescribable beauty." Artie, too, is making some headway on forgiveness.