Question: When do you find out who red coat is?

Disambiguated questions and answers:
context: In the fourth season's mid-season finale "Now You See Me, Now You Don't", the Liars head to Ravenswood to look for Red Coat. While there, Red Coat kidnaps Emily and locks her in a coffin on a Sawmill. The Liars witness Red Coat heading to that Sawmill and chase her inside, where she actually stops the saw and another Red Coat, donning a mask of Alison's face, appears on the stairwell, revealing that two people have been sporting the disguise all along. Spencer follows the Red Coat who saved Emily, while Aria fights the masked Red Coat and unmasks her as CeCe Drake. The Liars manage to catch the Red Coat who saved Emily in the ending of "Grave New World", who reveals herself as an alive Alison. During "Escape from New York", Ali claims that she asked CeCe to wear the disguise to distract "A" and that CeCe was never truly Red Coat. It is later revealed that CeCe actually was the Red Coat who stole the game from Mona and wore the disguise during her schemes, presumably until the saw mill incident. In "Game Over, Charles", the Liars learn there was a third Red Coat who posed as a decoy for CeCe and used the infamous disguise to distract the Liars whenever CeCe couldn't. The third Red Coat is revealed to be Sara Harvey.
question: What episode do you find out who the third red coat is?
short_answers: Season 6 Episode 10

Game Over, Charles

"Game Over, Charles"

130
wikipage: Red Coat (Pretty Little Liars)

context: In the fourth season's mid-season finale "Now You See Me, Now You Don't", the Liars head to Ravenswood to look for Red Coat. While there, Red Coat kidnaps Emily and locks her in a coffin on a Sawmill. The Liars witness Red Coat heading to that Sawmill and chase her inside, where she actually stops the saw and another Red Coat, donning a mask of Alison's face, appears on the stairwell, revealing that two people have been sporting the disguise all along. Spencer follows the Red Coat who saved Emily, while Aria fights the masked Red Coat and unmasks her as CeCe Drake. The Liars manage to catch the Red Coat who saved Emily in the ending of "Grave New World", who reveals herself as an alive Alison. During "Escape from New York", Ali claims that she asked CeCe to wear the disguise to distract "A" and that CeCe was never truly Red Coat. It is later revealed that CeCe actually was the Red Coat who stole the game from Mona and wore the disguise during her schemes, presumably until the saw mill incident. In "Game Over, Charles", the Liars learn there was a third Red Coat who posed as a decoy for CeCe and used the infamous disguise to distract the Liars whenever CeCe couldn't. The third Red Coat is revealed to be Sara Harvey.
question: What episode do you find out who the second red coat is?
short_answers: Now You See Me, Now You Don't

83

"Now You See Me, Now You Don't"
wikipage: Red Coat (Pretty Little Liars)

context: "Grave New World" is the 13th episode of the fourth season of the American mystery drama series "Pretty Little Liars". It originally aired on October 22, 2013 on ABC Family and serves as the season's Halloween episode, which aired as part of the "13 Nights of Halloween" programming block. The episode was directed by Ron Lagomarsino and written by Joseph Dougherty, Oliver Goldstick and I. Marlene King. The episode also serves as a backdoor pilot to the series’ spinoff "Ravenswood", which follows a group of people investigating the supernatural occurrences in the titular town. As a result, the episode features the spinoff's main cast as guest characters and some supernatural elements.
question: What episode do you find out who the first red coat is?
short_answers: Grave New World

13th episode of the fourth season

"Grave New World"

84
wikipage: Grave New World (Pretty Little Liars)

Long answers:
knowledge: content: Red Coat is a fictional character on the television show Pretty Little Liars, which was adapted from the book series of same name. Introduced during the second-season finale, she became the primary antagonist of the third and fourth seasons. In Season 4, it is revealed there are 2 active Red Coat's, one being CeCe Drake, the other being Alison DiLaurentis. In Season 6, it is revealed there is a third red coat, this one being Sara Harvey.
wikipage: Red Coat (Pretty Little Liars)
long_answer: In the show Pretty Little Liars, it is revealed that there are three red coat characters. The first red coat, Alison DiLaurentis, is revealed in the episode "Grave New World", which is episode 84 in the series and the 13th episode of the fourth season. The second red coat, CeCe Drake, is revealed in the episode "Now You See Me, Now You Don't", which is episode 83 in the series and the 12th episode of season 4. The third red coat, Sara Harvey, is revealed in the episode "Game Over, Charles", which is episode 130 in the series and is in Season 6 Episode 10.