Returning Champion;

For nearly 100 years, scientists have said that humans came to what is today the United States of America at the end of the last Ice Age, some 13,000 years ago. But new archaeological findings along the Savannah River in the southeastern United States show that a great migration could have happened as far back as 48,000 BC. Some believe these first settlers were gigantic prehistoric versions of homo sapiens. Megan Fox seeks to uncover who, or what, these early settlers really were.

Despite being given just two rules to abide at their annual Little People conference, Anna gets in trouble and faces severe consequences; once back home, Liz and Trent butt heads over driving lessons.

Twenty-three-year-old Sherry Leighty disappears from Altoona, Pa., leaving her three small children behind. After a 13-year search her sister discovers the rumor she skipped town with a new boyfriend is a lie and people close to Sherry have been hiding a dark secret.

A 40-ton boulder crashes onto B.C.'s Fraser Canyon Highway and launches Al Quiring into the crush zone; Jamie, Brandon, and Paris climb a deactivated logging road to retrieve a lost wreck.

A Corvette enthusiast has brought his 1963 Corvette to the right place. The car's had some work done, but he wants a huge LS X engine, a larger transmission, he wants to ditch the side pipes and developing a one-of-a-kind, stand-out paint color.

In a desperate attempt to get Chase to move to Nashville, Todd offers him their house that he's already promised to Savannah. Meanwhile the ladies can't get enough of Alison's new Hot pool instructor.

The experts return to the couples' home to see if they would live happily ever after.

An overturned load of heavy pipe becomes an all-out battle for Reliable Towing; Jamie considers buying another vintage wrecker; Mission Towing's Ken Duperon hustles to save a vehicle on the verge of sliding off a snowy mountain road.

New discoveries at a strange prehistoric site reveal the dark secrets and rituals of the mysterious people who built the world's largest stone circle, three times bigger than Stonehenge, and just as enigmatic.

A police officer tracks down an armed carjacker and comes under heavy fire. A stabbing in broad daylight forces the police to take decisive action. A routine traffic stop results in an officer being shot and fighting for his life.

Marcus travels to Santa Claus, Ind., to save Santa's Toys; hardworking owners Mark and Heidi's business practices have landed their business on the naughty list, and they must follow Marcus' protocol to save their business.

Dave is in an unhappy marriage and uses his family vacation as an excuse to finally stand up to his nagging wife. But the stress of the event sends Dave on an adventure he could have never dreamed of.

Todd ponders the first half of his life as his 50th birthday approaches. Meanwhile, Grayson clamors to be left home alone now that he's 12 years old.

Rapper Pusha T.

Emily Blunt; Rep. Adam Schiff; musical performance by St. Paul & The Broken Bones.

Singer/author Pharrell Williams; talk and musical performance by Gwen Stefani; comedy performance with Lin-Manuel Miranda and Emily Blunt.