Purgatory by Tim Dodge

Charles Cunningham, a wealthy real estate developer, dies unexpectedly and finds himself in Purgatory, the place between heaven and hell. Though depressed about his early death, he befriends two other souls doing time there --  the writer Edgar Allan Poe and a music-loving deadbeat named Billy. Upon receiving a letter from God telling him he must learn some unnamed lessons before he can go to heaven, he convinces Poe to join him in the portal back to earth. They hope to make up for their past mistakes, but they arrive on earth in the year 2049, 42 years after Charles' death. Traveling from mid-21st century New York City to Las Vegas, Charles seeks out the daughter he neglected in life, though she is now in her eighties. However, an unfriendly soul from Purgatory follows them to earth. This soul, an employee with whom Charles had an affair and summarily fired, is determined to keep him from winning passage to heaven. She teams up with Charles' grandson, a debt-ridden gambling addict who has a talent for messing things up. Together, they hatch a deadly scheme to foil Charles' plan to get to heaven and net the grandson badly-needed money. Charles learns of their plans and enlists his friends to help stop them. Will they succeed?The only way to find out is to subscribe.