A Shrouded World 4: Valhalla: A Jack Walker and Michael Talbot Adventure

Mark Tufo writes horror and post-apocalyptic fiction. He is the author of Zombie Fallout, The Trembling Path, United States of Apocalypse 3, and At Hell's Gates.

John O'Brien writes historical non-fiction. He is known for works such as Quien Fue Franklin Roosevelt? His books offer straightforward accounts of historical figures.