Travel back 66 million years to when majestic dinosaurs and extraordinary creatures roamed the lands, seas, and skies in the second season of this acclaimed series narrated by David Attenborough.
After a tropical storm, two Zalmoxes find themselves in a rafting event. On a small island, a monumental display takes place as several Hatzegopteryx ambush a herd of Tethyshadros. A female Majungasaurus hunts a group of Simosuchus. A mother Adalatherium raises her offspring in a burrow, hoping to keep them safe from predators like Masiakasaurus and Madtsoia. A pack of Imperobator pursue a Morrosaurus onto a frozen lake. A male Hatzegopteryx attempts to attract a mate.

The series follows the tragedy that occurred when terrorists attacked at the annual Boston Marathon on April 15, 2013. They carried out the attack by placing two homemade pressure cooker bombs which detonated near the finish line of the race 14 seconds and 210 yards (190 m) apart. That resulted in three fatalities and hundreds injured, including 17 who lost limbs. With the help of archive footage, interviews with investigators, witnesses, survivors, and occasional reenactments, it offers details about the FBI investigation into what was quickly deemed a domestic terrorist attack.
In the first episode, hours after the blasts, investigators pore over evidence. One photo and a few seconds of footage lead to a breakthrough - and an agonizing choice.

The images of brothers Tamerlan and Dzhokhar Tsarnaev are released to the public setting off a violent chain of events. Meanwhile, clues from their past tell a complicated story - how was the radicalization of the ethnically Chechen brothers and the existence of potential collaborators. The post-9/11 biases played a role in the investigation.

Following their identification, the Tsarnaev brothers killed an MIT policeman, then kidnapped a man in his car. They had a shootout with the police in nearby Watertown, during which two officers were severely injured (one of whom, Dennis Simmonds, died a year later). Tamerlan was shot several times, and his brother Dzhokhar ran him over while escaping in the stolen car. Tamerlan died soon after.
An unprecedented manhunt for Dzhokhar ensued, with thousands of law enforcement officers searching a 20-block area of Watertown. Residents of Watertown and surrounding communities were asked to stay indoors, and the transportation system and most businesses and public places closed. After a Watertown resident discovered him hiding in a boat in his backyard, Dzhokhar Tsarnaev is cornered into an intense standoff. As officials navigate remaining questions and suspicions, the city emerges Boston Strong.

Dave Paulides investigates cases of elk hunters who've gone missing from specific regions of North America, and explores the theory that there could be a connection between these disappearances and sightings of UFOs. This project brings together top officials from the FBI, local law enforcement, search team members and others that describe a spell-binding fact trail that will leave the viewer asking more questions than officials are willing to answer.

Pterosaur hatchlings take flight to leave their island sanctuary, but are targeted by several Shamosuchus. Several Austroraptor hunt garfish and contend for the best fishing spots. A male Beelzebufo attempts to attract a mate, but his endeavor is interrupted by a herd of Rapetosaurus. A male Pachycephalosaurus must put an upstart youngster in his place. Two Tyrannosaurus brothers hunt Edmontosaurus under the cover of darkness.