After classes the Colonel announces that he has a theory about Alaska: someone calls (he thinks Jake, her boyfriend), they fight, she cries, she freaks out, and then she drives away.
Miles doesn't want to believe this because Alaska was making out with him, not Jake. He has so many questions, but he's worried about their answers.
The Colonel wants to solve the mystery; Miles doesn't. Or does he? It's really complicated.
Convinced that Alaska was going to leave Jake for him, Miles doesn't even want to talk to Jake. But he goes along with the Colonel's game plan of talking to eyewitnesses, figuring out how drunk she was, and figuring out where she was going.