Stephen Kinzer explains the twisted life of Sidney Gottlieb, a CIA operative who tortured and poisoned for a supposed greater good. Former CIA Chief of Counterintelligence James M. Olson on what it takes to catch a spy. Sonia Purnell tells the story of Virginia Hall, a highly unlikely but most dangerous Allied spy in WWII.

Clive Wynne breaks down the psychology behind dogs and why they love us. Phyllis Meuller is the chief of staff for Maximus Mighty-Dog Meuller II, the only dog who serves as mayor. Sy Montgomery explains why wild dogs are not necessarily mans best friend.

Jennifer Ackerman reveals that birds' social lives often rival our own. Harvard's Irene Pepperberg describes the humor and intelligence of her famous African grey parrot. Erik Swanson, of East Coast Falcons, uses raptors to solve the Jersey Shore’s seagull problem. Marcus Smith explains the aviary origins of well-known English phrases.

Joshua Mezrich share a day in the life of a transplant surgeon. Jens Puschhof of Hubrecht Institute shares his groundbreaking research growing organs in a lab.

Derek Gow is a beaver crusader with a mission to bring back beavers to the world's waterways. Andrew Reeves explains why Asian Carp have become a huge problem in America's river systems, even as they become endangered in their native habitats.

Judith Sumner breaks down the botanical history of WWII to show how plants played a significant role, for good and ill, on both sides of the war. David Taylor explains that cork was essential in construction of WWII battleships.

Judith Sumner breaks down the botanical history of WWII to show how plants played a significant role, for good and ill, on both sides of the war. David Taylor explains that cork was essential in construction of WWII battleships.

Nicholas A. Basbanes tells the rich story of famous poet Henry Wadsworth Longfellow. Daniel Peterson of BYU examines the mystery of the Magi.

Nicholas A. Basbanes tells the rich story of famous poet Henry Wadsworth Longfellow. Daniel Peterson of BYU examines the mystery of the Magi.

Judith Flanders shares all the types of Christmas traditions that have arisen in the almost 2000 year history of Christmas. Kim Balaschak explains the Russian tradition of New Year's Ornaments.