Twenty returning castaways, who were voted in by fans, arrive in Koh Rong, Cambodia, an island in the South China Sea, for a second chance to win the top $1 million prize as the 31st season begins.

A classic immunity challenge leaves one tribe puzzled, while a contestant hopes an apology will help prevent an elimination.

The castaways switch from two tribes to three and a castaway is caught sending a message to another tribe.

There is a gut-wrenching challenge and contestants plead for their place in the game at a heated tribal council; Abi-Maria keeps ruffling feathers.

A castaway embraces a more personal style of play; another castaway goes against her own alliance, potentially ruining a good thing.

A family emergency forces a contestant to leave the game as a classic immunity challenge features local delicacies.

Thirteen castaways form the largest merge in the history of the competition; two castaways feud and the individual immunity challenge is a game of balance.

Castaways thirst for a much-needed reward after an intense water challenge while a tribal council takes a surprising turn.

A castaway puts personal safety at risk in hopes of gaining an advantage. There's a brutal immunity challenge and three castaways, known as Witches Coven, stir things up.

Relentless rain drowns the players' spirits, but a fun reward reveals a glimpse of Cambodian culture; the voting block strategy keeps castaways on their toes.

The castaways' emotions run deep when loved ones visit the island, plus there's a desperate reward challenge; during an immunity battle, exhaustion takes its toll.

The castaways scramble to form a plan for the final three, while a frightening incident shocks the tribe; the castaways are rewarded with a visit to temples in Cambodia.

Six castaways compete for a spot in the top three, but a "Survivor" first occurs during a shocking tribal council; the three finalists battle for the $1 million prize.

The castaways reunite in Los Angeles to discuss the season. Jeff Probst hosts.