Matt Dillon is very perceptive. He can see that Ascombe hates Cass and probably wants to kill him. In Part 2, Matt tries to prevent a murder. Ascombe won’t tell Matt why he wants to kill Cass, so Matt goes in search of Cass. He wants to hear Cass’s side of the story. There must be an incident that happened in the past that triggered this. If only Matt could understand the missing motive behind Ascombe's hatred of Cass, he could help the two men negotiate and reconcile.