In the play's moving--and ironic--conclusion, Tom (as narrator) recounts what his life had become after leaving home. He had achieved freedom without ever being free:
I traveled around a great deal. The cities swept about me like dead leaves, leaves that were brightly colored but torn away from the branches.
I would have stopped, but I was pursued by something.
What pursues Tom, as he explains it, is the memory of his sister:
Oh, Laura, Laura, I tried to leave you behind me, but I am more faithful than I intended to be!
Tom cannot escape his memories of Laura and his own guilt for leaving her. His love for her and his understanding of her fragile and vulnerable life were all that had kept him at home for as long as he had managed to stay. He was emotionally trapped at home, and he remained emotionally trapped after leaving. There is no escape for Tom; he cannot escape his own character, no matter where he runs or what he does:
I reach for a cigarette, I cross the street, I run into the movies or a bar, I buy a drink, I speak to the nearest stranger--anything that can blow your candles out!
In a further irony, after leaving home Tom still turns to the same methods of escape that he employed while living in the St. Louis apartment with Laura and Amanda. They did not work for him then, and they do not work for him in his "new" life. The past controls his present, and there is no reason to believe it will not control his future.