All 13 couples return to perform; musical performances by Alexander Jean, Andy Grammer, Chaka Khan, Elle King and Nick Carter; the winner is announced.

The finalists compete in two rounds of dance, one in which a judge helps the couples choose the creative elements and a freestyle number; performances by Meghan Trainor and Ariana Grande.

The couples take on a style of dance that hasn't been performed yet, a trio and a dance-off challenge.

For the first routine, the couples will reveal a dance style not yet performed this season. Later in the show, they will be moved into teams to perform a side-by-side dance. Inspiration for the team routines were drawn from each teams' travels around the country to experience live productions of famous shows such as The Beatles(TM) LOVE(TM) by Cirque du Soleil(R), Broadway's Chicago and Royal Caribbean's "We Will Rock You." At the end of the night, one couple will be eliminated.

Performances honor influential figures in the celebrities' lives; one couple is eliminated.

The eight remaining couples will perform an individual Halloween-themed routine in addition to a competitive team dance. For the team dances, the cast has been divided into two frightening teams: Team #Nightmare and Team #WhoYouGonnaCall. These two teams will compete against each other, vying for a perfectly wicked score from the judges. Actress and "Dancing with the Stars" Season 17 semi-finalist Leah Remini also returns to guest co-host alongside Tom Bergeron. At the end of the night, one couple will face elimination.

Olivia Newton-John steps into the ballroom to help judge the remaining nine couples as they perform iconic dance routines from movies and music videos.

Pro Maksim Chmerkovskiy returns to guest judge as the celebrities and professional dancers switch partners for one week.

The couples dance to songs that represent a significant year in the celebrities' lives for Most Memorable Year night; a couple are eliminated.

For TV Night, the couples dance to a song that celebrates iconic shows; Season 19 champion Alfonso Ribeiro returns as a guest judge.

Dances commemorate the dance pro's hometown. One couple is eliminated.

Couples dance to a song that commemorates the celebrity's hometown. One couple is eliminated.

A recap of dances from the first episode of the season. Also: interviews and rehearsal footage; a preview of the second week of performances.

Dancing with the Stars is back with an all-new celebrity cast hitting the ballroom floor. The Season 21 premiere episode kicked off with the biggest number in DWTS history shot on the famed Hollywood Boulevard. The night continued with each couple dancing a Cha Cha, Foxtrot, Salsa, Quickstep or Jive, vying for America's vote for the first time.