Bill Posley

A close friend of Mac's from MIT fakes her own death to stop someone from assassinating her because of her scientific research.

Weathering the harsh elements sparks new battles between the sexes, and poor communication leaves castaways scrambling at a frustration-filled Immunity Challenge, on `Survivor One World'.

It's a battle of the sexes when tribes are separated into men versus women, but they are in dismay when they learn of a game-changing twist they must share one beach.

An unforgivable betrayal forces one tribe to make a drastic move that has never been seen before in `Survivor' history, and an electrifying Tribal Council leaves several castaways speechless.

Castaways jump off the deep end in an Immunity Challenge that requires a delicate balance. Meanwhile, a group of misfits band together, finding an unlikely leader, on Survivor One World.

The winner is revealed as the 18 castaways reunite to discuss the season.