I personally think your omg moment is going to be Rust and Marty getting to the end of the trail, but being killed just before the two new detectives find another pair of kids locked away.
The last two episodes have repeatedly foreshadowed that the path that Rust and Marty have resumed is all but a suicide mission. Marty basically saying goodbye to his ex and wrapping up lose ends, her knowing and asking Rust to not get Marty involved in something that will get him hurt, Rust constantly referencing the debt they need to pay, their willingness to kidnap and hold a powerful sheriff at gun point and Rust's comment that he hopes the lady's death is not the end comment is wrong all point to this being a one way street for the two. I think they will solve the case but their solution will never see the light of day and the next two detectives will pick up the trail by finding two kids in a container. Thus, death not being the end of the investigation, but despite their efforts, the circle is not broken and no matter what is done the same events, only with different players, are going to unfold no matter what happens. But in the end their debts will be paid.
Comment