The following episode synopses come from several sources, including the US laserdisc boxed set of first season episodes and the book "The Television Yearbook (1990-91)" by Frank Lovece, covering second season episodes.

FIRST SEASON

Pilot (1000)

Original airdate: April 8, 1990

Laura Palmer's body is discovered, wrapped in plastic; Ronette Pulaski wanders out of the woods; FBI Agent Dale Cooper arrives in Twin Peaks to investigate and finds an unusual clue on Laura's body; Audrey Horne disrupts her father's negotiations with some Norwegian businessmen; Cooper and Sheriff Truman discover the grisly murder site in the woods, and warn the town that the killer may be from their community; tempers flare at the Roadhouse.

Episode 1 (1001)

Original airdate: April 12, 1990

FBI Agent Dale Cooper and Sheriff Harry Truman discover more about the troubled secret life of the murdered Laura Palmer; Big Ed Hurley reveals that he was drugged at the Roadhouse; a frightened James Hurley, vengeful Bobby Briggs and Mike Nelson are released from jail; Catherine Martell lays bare her plot to take control of the Packard sawmill.

Episode 2 (1002)

Original airdate: April 19, 1990

FBI Agent Dale Cooper demonstrates an unusual deductive technique for the Twin Peaks Sheriff's Department; Benjamin Horne and his brother, Jerry, take a trip to One-Eyed Jacks; Donna Hayward and James Hurley pledge their love; Leo Johnson holds Bobby Briggs at gunpoint; Cooper has a strange dream.

Episode 3 (1003)

Original airdate: April 26, 1990

The townsfolk of Twin Peaks gather for Laura Palmer's funeral; Cooper interprets his dream about the killer; Truman reveals to Cooper the secret of the Bookhouse Boys.

Episode 4 (1004)

Original airdate: May 3, 1990

Cooper and Truman track down the one-armed man and some strange new evidence in Laura Palmer's murder; Norma Jennings attends a parole board hearing for her husband; Audrey Horne decides to begin her own investigation.

Episode 5 (1005)

Original airdate: May 10, 1990

Cooper and Truman have tea with the Log Lady and discover a macabre crime scene in the woods; Audrey Horne takes a job at her father's department store; Hank Jennings returns from prison to the Double R Diner; James Hurley and Donna Hayward take Madeleine Ferguson into their confidence.

Episode 6 (1006)

Original airdate: May 17, 1990

Agent Cooper and Big Ed pay a special visit to One-Eyed Jacks, while Audrey Horne goes undercover as a hostess there; Josie Packard shares her suspicions with Truman about Catherine Martell's intentions; Dr. Jacoby receives a phone call from the dead Laura Palmer.

Episode 7 (1007)

Cooper and Truman's investigation builds to a terrifying conclusion; Dr. Jacoby heads for his rendezvous with "Laura Palmer"--and its bizarre consequences; Catherine Martell and Shelly Johnson are hopelessly trapped; Hank Jennings' evil influence spreads, engulfing Josie Packard.

SECOND SEASON

Episode 8 (2001)

Original airdate: September 30, 1990

A shot and bleeding Agent Cooper has visions of a giant; Audrey is imprisoned at the casino/bordello One-Eyed Jacks; Donna receives a strange message; Josie and Catherine are missing; a stirring Ronette relives Laura's murder.

Episode 9 (2002)

Original airdate: October 6, 1990

Cooper learns his ex-partner, Windom Earle, has escaped from a mental asylum; Major Briggs gives Cooper a message; Donna meets an eerie old woman and her grandson; Ben orders Leland killed; Deputy Andy thinks he's sterile; Audrey learns more about Laura, but is uncovered by a vengeful Blackie.

Episode 10 (2003)

Original airdate: October 13, 1990

Donna finds a diary of Laura's at Harold Smith's house; Blackie holds Audrey hostage, and plots with Jean Renault; James and Madeleine become close, to Donna's dismay; Lucy lunches with Dick Tremayne; Dr. Jacoby undergoes hypnosis, leading to an arrest.

Episode 11 (2004)

Original airdate: October 20, 1990

Cooper is stymied by an unusual request from Ben Horne to save Audrey's life; Josie introduces her "cousin" Jonathan from Hong Kong; Renault deals with Battis.

Episode 12 (2005)

Original airdate: October 27, 1990

Cooper and Truman stage a raid on One-Eyed Jacks; Leland attends his court hearing; Donna and Madeleine plot to steal Laura's secret diary from Harold Smith; Ben gets a business proposition.

Episode 13 (2006)

Original airdate: November 3, 1990

Donna and Madeleine fear an enraged Harold Smith; Shelly and Bobby, hold a "welcome home" party for the comatose Leo; Cooper's boss, Gordon Cole, visits to warn Cooper of threats; Josie strieks a deal with Ben and leaves with Jonathan; the one-armed man reveals some information about "Bob".

Episode 14 (2007)

Original airdate: November 10, 1990

Ben is brought in for questioning after Audrey confronts him about One-Eyed Jacks and passes the information to Cooper; Andy ponders the meaning of Harold Smith's note; having misjudged the money due them, Shelly and Bobby are cash-strapped; Bobby finds a microcassette of Leo's; Madeleine prepares to go home; Pete learns Tojamura's plans.

Episode 15 (2008)

Original airdate: November 17, 1990

Norma's visiting mother introduces her new husband, unaware of his connections to Hank; Lucy returns, with her sister; Bobby decides to blackmail Ben, who also gets a tape-recorded ultimatum; the one-armed man leads to a grisly discovery.

Episode 16 (2009)

Original airdate: December 1, 1990

From a piece of Laura's secret diary, Cooper discovers he and Laura shared the same dream, with her message in it leading him to her killer; Catherine tricks Ben into signing away the mill; Lucy, Andy and Tremayne confront each other over her pregnancy.

Episode 17 (2010)

Original airdate: December 8, 1990

As Cooper says his goodbyes, an FBI agent arrives to suspend him and investigate the unauthorized One-Eyed Jacks affair; the publisher of the Twin Peaks Gazette argues with his brother, the Mayor; Renault recruits Hank and Ernie to frame Cooper; Nadine, deluded that she's a teenager, enrolls in high school; Major Briggs, fishing with Cooper, has a strange encounter in the woods.

Episode 18 (2011)

Original airdate: December 15, 1990

Cooper is investigated by the FBI and the DEA; Nadine falls for teen Mike Nelson; James gets room and board for helping a beautiful blond; Hank confronts Ben; Tremayne becomes Big Brother to a terror; Catherine forces Josie to become her maid; Andrew Packard turns up alive.

Episode 19 (2012)

Original airdate: January 12, 1991

Cooper finds cocaine at a deserted house Renault uses; Andy and Tremayne confront concerns of Nicky's past; a mentally decaying Ben has Bobby tail Hank; Dougie Milford dies under unusual circumstances; supernaturally superstrong Nadine joins the wrestling team; Major Briggs returns.

Episode 20 (2013)

Original airdate: January 19, 1991

Cooper is held hostage by Renault; Andy and Tremayne pry into Nicky's past; Catherine professes her love for Ben; James succumbs to a treacherous Evelyn; Ed and Norma succumb to each other; Hank confronts Big Ed; Cooper's ex-partner Windom Earle makes a move.

Episode 21 (2014)

Original airdate: Febuary 2, 1991

Cooper confides to Truman his past experiences with Windom Earle; Earle meanwhile takes in Leo; Audrey strikes a business deal with Bobby; James realizes he has been set up; Josie's dangerous old lover, Thomas Eckhardt, appears.

Episode 22 (2015)

Original airdate: February 9, 1991

Cooper finds some evidence about who shot him, and gets help from the town's resident chess master in matching wits with Windom Earle in the deadly chess game; Donna makes a desperate plea to save James; Nadine surprises Ed and Norma; Catherine uses Josie to lure Eckhardt.

Episode 23 (2016)

Original airdate: February 16, 1991

Ed proposes to Norma; James and Donna break up; Audrey meets a handsome, wealthy admirer from her past; Earle mails a puzzle to Audrey, Shelly and Donna; Josie makes a confession, after a dreaded encounter with Thomas Eckhardt; Cooper has another vision.

Episode 24 (2017)

Original airdate: March 28, 1991

Cooper is attracted to Norma's sister, Annie, returning to the world from a convent; Truman withdraws from everyone; Donna receives a macabre family visitor; Audrey falls for Wheeler; Nadine and her teenage beau Mike Nelson check into the Great Northern Hotel; Ben hosts an environmental benefit.

Episode 25 (2018)

Original airdate: April 4, 1991

Cooper and the Sheriff's Department go spelunking in Owl Cave; Truman awakens in the murderous embrace of a naked woman; Windom Earle insinuates himself into the lives of potential victims; Audrey and Donna see Mrs. Hayward meet with Ben.

Episode 26 (2019)

Original airdate: April 11, 1991

Cooper and Truman try to decipher the hieroglyph from Owl Cave; plans for the Miss Twin Peaks contest get underway; Tremayne holds a wine tasting at the Great Northern Hotel; Cooper falls for Annie, and Gordon for Shelley; Windom Earle makes his next move.

Episode 27 (2020)

Original airdate: April 18, 1991

Cooper and Truman continue to investigate the mystery of Owl Cave; Windom Earle snares Major Briggs; Cooper romances Annie; Donna makes a discovery on her birth certificate; Wheeler leaves suddenly after receiving urgent news.

Episode 28 (2021, Part 1)

Original airdate: June 10, 1991 (broadcast as a 2-hour "movie" with episode 29)

Cooper and Truman decipher part of the secret of the Black Lodge; Cooper helps Annie prepare for the Miss Twin Peaks contest; Major Briggs escapes from Earle; Catherine continues her battle with the black box; Lucy chooses the father of her baby; Earle interrupts the contest.

Episode 29 (2021, Part 2)

Original airdate: June 10, 1991 (broadcast as a 2-hour "movie" with episode 28)

Cooper and Truman figure out the location of the Black Lodge, and rush to save Miss Twin Peaks there; Nadine regains her senses; Donna confronts her parents about Ben; Audrey stages an act of civil disobedience; Cooper enters the Black Lodge.