The Day After Roswell investigates the alleged crash of a UFO near Roswell, New Mexico, in 1947 and its subsequent cover-up by the U.S. government. The book presents testimony from individuals claiming to have been involved in the recovery and study of alien technology and bodies. It aims to expose what the authors believe is a decades-long conspiracy to conceal the truth about extraterrestrial visitation.

The book presents a controversial thesis regarding the Roswell incident, drawing on numerous interviews and alleged insider accounts. While it has been influential in popularizing certain aspects of the Roswell narrative, its claims are largely dismissed by mainstream historians and scientists. The work is often cited within UFOlogy circles as a key text, though its factual basis remains a subject of intense debate and skepticism.