The Beast evolves again with a new obstacle called "Rib Cage Row," and two of nine contenders will grab the first spots in the second semifinal.

The "Crash Pads" return, and a twisty new obstacle greets a group that includes the competition's youngest athlete and a cancer survivor.

A group that includes a war hero and a survivor of Rwandan genocide confronts the hungry Beast with the last two semifinal berths at stake.