Some think at the end it is hinted that Paul Radin merely imagines the whole meeting with the three people who wronged him and that he really had no such meeting, bomb shelter or anything. But actually Radin's imagination only takes over when he goes out into the part of NYC right outside his building. Notice when the cop is really standing over Radin you see Radin's building is indeed marked "Radin" --thus he is actually a millionaire with a bomb shelter.