What is the narrator's role in the play? What would be gained or lost without him?

Tom is our narrator, a number of years after the story's occurrences. Because he was a part of the action, we know that his memories are colored. Thus, we may not have a completely accurate description. Things are surely altered to "his" memory, he may lack objectivity, and he may purposefully alter the truth to reflect what he felt as opposed to what really happened.