The Hemingway Hoax (Unabridged‪)‬

The hoax proposed to John Baird by a two-bit con man in a seedy Key West bar was shady but potentially profitable. With little left to lose, the struggling, middle-aged Hemingway scholar agreed to forge a manuscript and pass it off as Papa's lost masterpiece. But Baird never realized his actions would shatter the history of his own Earth - and others. And now the unsuspecting academic is trapped out of time - propelled through a series of grim parallel worlds and pursued by an interdimensional hitman with a literary license to kill.
BONUS AUDIO: Author Joe Haldeman explains how, fittingly, the idea for The Hemingway Hoax wasn't entirely his.