In the television series "Arrow", how come Oliver Queen doesn't rescue Walter sooner than he did?
He didn't have any solid leads to go on. He didn't know where he was being kept before he eavesdropped on Malcolm and he only did that because he was following his mother after she reacted strangely on the news Walter was dead. He only got that news after his last act of cleaning up the neighbourhood got him the clue he needed.
If he knew where he was in the first place, he wouldn't of believed the mob guy (saying Walter was dead).