"Last Dances & Last Chances" is the seventeenth episode in Season 3 of Austin & Ally. The episode aired on August 24, 2014. This was the 16th episode to be filmed in Season 3. The episode earned 2.215 million views on it's premiere night.
Carrie threatens to tell her sister Piper, who happens to be Austin's prom date, that he'd rather be at the prom with Ally. Meanwhile, Piper is growing suspicious of Austin's relationship with Ally.
The episode starts off with flashbacks from the previous episode, then picks up where the last episode left off. Carrie decides not to tell Piper the truth,but then threatens to ruin Austin's night if he doesn't make it special for Piper. Ally then walks up to Austin and Piper, and Austin tries to act normal around Piper, but hurts Ally's feelings in the process.
In the second scene, Dez walks up to Austin. Austin then confesses to Dez that he would rather be with Ally than with Piper, much to Dez's happiness. When Piper walks up to them both, and Carrie, Dez gets nervous and runs off, making Piper ask Austin what's wrong with him.
Meanwhile, Trish is now having to deal with hanging around both Jace and Chuck, but its more difficult than she thought. Dez comes over to Austin and asks him to his dance partner for the compertition, but he says no. Kimmy then announces that Austin and Ally have won prom king and queen much to their shock, and they then share a tight hug, making Piper become even more upset about Austin's feelings for Ally. When they are dancing, Austin leaves Ally to speak to Piper, and Dez dances with Ally instead.
In the next scene, Austin breaks up with Piper to be with Ally. Piper takes it surprisingly well, figuring it better to find out then than later, and convinces Austin to let Ally know how he feels. (However, she does insist that Austin tell Ally Piper broke up with him instead of the other way round.)
Austin then comes back in. He's just about to tell his feelings to Ally when Gavin turns up, much to Ally's surprise and Austin's annoyance. Ally then goes outside and breaks up with him to be with Austin and goes back inside.
In the next scene, Dez and Trish compete in the dance contest together since their dates can't dance, and they win the contest. Kimmy then says the money will be used for Chuck's club instead, annoying both Dez and Trish.
In the next scene, Ally comes back in, and walks up to Austin after breaking up with Gavin, and tells him this, and Austin then says he broke up with Piper, much to Ally's suprise. Slow, romantic music then plays in the background, and Austin then asks Ally to dance, and she happily says yes. When they're dancing, Ally asks Austin why he broke up with Piper, and he then admits he still has feelings for Ally, and she says she still has feelings for Austin, too, and they both have never stopped having feelings for each other. Austin then asks Ally out and she happily says yes. They then share their third kiss, hug and finally get back together, with Trish and Dez watching in the background.
In the final scene, Dez is seen dancing with Carrie, and Trish is seen dancing with Jace. Jace then reveals that he found out that Trish went to prom with Chuck, much to her shock, and he knows she wanted the prize money to see Jace, making her happy. Austin and Ally are then seen dancing romantically, and Ally then says her night turned out perfect, because she was with Austin, and they are seen dancing again, and the episode then ends.