On this edition of Conversations, Marta McDowell talks with host Dan Skinner about “Unearthing The Secret Garden – The Plants and Places that Inspired Frances Hodgson Burnett.” McDowell consults for public gardens and private clients, writes and lectures on gardening topics, and teaches landscape history and horticulture at the New York Botanical Garden.

Who was Umberto Nobile? On this edition of Conversations, Mark Piesing talks with host Dan Skinner about “N-4 Down: The Hunt for the Arctic Airship Italia.” Piesing has written for the BBC, “The Guardian,” “The Economist” and “Wired.” The crash of the Airship Italia led to the largest polar rescue mission in history.

On this edition of Conversations, Martin Dugard talks with host Dan Skinner about “Taking Paris: The Epic Battle for the City of Lights.” Dugard is a bestselling author and historian who has written on topics ranging from presidents to Egyptian pharaohs. He is the coauthor of the popular “Killing” series as well as the author of “Into Africa,” “The Explorers” and “The Murder of King Tut."

On this edition of Conversations, Lauren Tarshis talks with host Dan Skinner about the graphic novel adaptation of her bestselling “I Survived: The Attacks of September 11, 2001.” This new edition of the book was released to mark the 20th anniversary of 9/11. Tarshis is the New York Times bestselling author of the “I Survived” series which tells stories of young people and their resilience and strength during times of disaster and turmoil.

On this edition of Conversations, Andrew H. Knoll, talks with host Dan Skinner about “A Brief History of Earth: Four Billion Years in Eight Chapters.” Knoll is the Fisher Professor of Natural History at Harvard University. Professor Knoll’s research focuses on the early evolution of life, Earth’s environmental history, and the interconnections between the two.