The main idea for chapter 20 of percy jackson the lighting theif? using tex r evidence

They stumble onto the Santa Monica Beach at sunrise, while Los Angeles burns behind them. They walk for miles on the beach discussing what has just happened. Percy realizes that someone other than Hades stole both the master bolt and the helm of darkness and framed Percy because his dad is Poseidon:

Poseidon will get blamed by both sides. By sundown today, there will be a three-way war. And I'll have caused it. (20.13)

In the distance, they see Ares on his motorcycle with a baseball bat, waiting for them. Percy accuses him of stealing the helm of darkness and the master bolt.