Red Flag Laws – In the wake of mass shootings, states have turned to "Red Flag" laws, allowing law enforcement temporarily to remove firearms from someone posing a threat. Colorado just passed the law, but residents there are fiercely divided. Half the counties have declared themselves second amendment sanctuaries, with some sheriffs vowing not to enforce the law. Scott Pelley reports.

Into the Deep – The ocean floor holds trillions of dollars worth of metals essential to the production of supercomputers, electric cars, and cell phones. While other countries begin efforts to mine them, the U.S. is left out because it failed to sign a U.N. treaty. Bill Whitaker reports.

The Youngest Refugees – Sesame Street is bringing a new gang of Muppets to the Middle East. The creators of the legendary children's show and the International Rescue Committee have joined forces to address the needs of Syrian child refugees. Lesley Stahl reports from Jordan.

YouTube – Wildly successful but often lit up by controversy, the video-sharing site has its pros and cons. Lesley Stahl talks to its CEO, Susan Wojcicki, about its policies.

Unsheltered – Seattle, Washington is one of the fastest-growing cities in America and one where the homeless crisis is among the most visible. Anderson Cooper goes there to report on how one city is dealing with what has become a national problem.

Built by Angels – Ethiopian pilgrims have been trekking to this mysterious holy site for centuries to visit its rock-hewn churches carved out of the African plateau. Scott Pelley made the trip in time for the Ethiopian Orthodox Christmas vigil and tells this remarkable story.