Background

It has taken many years and numerous efforts by a multitude of people over the course of his life, but finally J.R. Ewing (Larry Hagman) has been reduced to practically nothing. He has lost control of the Southfork ranch, which was given to Bobby (Patrick Duffy) by Clayton Farlow (Howard Keel) after he decided to spend more time traveling with Miss Ellie (Barbara Bel Geddes).

J.R.'s business empire has also crumbled. Clayton gave him voting power on the board at WestStar Oil, but through the scheming of Clayton's son Dusty (Jared Martin) and WestStar executive Carter McKay (George Kennedy), J.R. was tricked into selling the controlling stake in Ewing Oil to his archenemy, Cliff Barnes (Ken Kercheval). After McKay revealed the ruse to J.R., he promptly fired him from WestStar and left him with no form of employment. Additionally, J.R.'s long-time secretary Sly Lovegren (Deborah Rennard) left Ewing Oil to marry, and Bobby's secretary Phyllis Wapner (Deborah Tranelli) refused to help J.R., telling him that "Hell would freeze over" before she worked for him.

Finally, J.R. lost his closest family member as his son and namesake John Ross (Omri Katz) disowned him, deciding to stay in London to be with his mother Sue Ellen (Linda Gray) and her new husband Don Lockwood (Ian McShane). The fallout from these events appeared to be too much for J.R. to bear, and as the penultimate episode drew to a close, he procured his father Jock’s pear handled six-shooter from his nightstand.

Events

In the intervening time between the end of the previous episode and the beginning of this one, J.R. has consumed a significant amount of bourbon whiskey and is walking around Southfork in a drunken stupor. He is still holding Jock’s revolver, and is seriously considering whether or not to turn it on himself and end what is left of his life.

A spirit named Adam (portrayed by Joel Grey) pays a visit to J.R., who cannot believe what he is seeing. The white tuxedo-clad Adam tells J.R. his "boss" likes him and has dispatched him to Earth. In a parallel with the storyline of the movie It's a Wonderful Life, Adam proceeds to take J.R. on a journey to show him what life would have been like for other people if he had not been born. Among what he shows him:

• J.R.'s place as eldest Ewing child would have been taken by Gary (Ted Shackelford), who would also take over for J.R. as heir to the Ewing Oil fortune. Bobby thus becomes the middle brother, and the Ewings would have a third son named Jason (Patrick Pankhurst).
• Since Gary was not anywhere near the oil man that his brothers were, Ewing Oil went bankrupt under his watch. As such, Jock committed suicide when the company went bust. Heartbroken, Miss Ellie had the coroner record his cause of death as a stress-related illness, and herself died two years later, blaming herself for having forced Jock to hand the company over to Gary, and never meeting Clayton Farlow. The non-existent Jason would have become a shady real estate developer and cheating husband who would eventually trick Bobby and Gary into selling their stakes in Ewing Oil and Southfork, leaving the property in his hands once his parents died. This would result in the destruction of the ranch in favor of "Southfork Estates", a development of tract houses built in its wake. Jason would also become a family pariah, as Gary wants nothing to do with him and Bobby was swindled out of $500,000 in a bad real estate deal of his.
• Having never met Pam due to there being no rivalry between J.R. and Pam's brother Cliff, and due in part to losing all of his savings in Jason's deal gone wrong, Bobby's wild ways caught up with him and he became a down-and-out hustler owing thousands in gambling debts and child support which he cannot pay. Carter McKay is connected with his gambling debts, as due to his firing at WestStar Oil he went into the casino business in Las Vegas. Bobby later settles his debt, but Adam tells J.R. it will not be the last time he runs into money trouble.
• Gary spent his life becoming a successful divorce lawyer in Beverly Hills, who never married and thus never had J.R.'s niece Lucy. However, he still meets Valene Clements - in this universe, Valene Wallace - who is seeking an inheritance from her late husband's estate. They agree to go on a date together, and Adam hints that Gary and Val were always destined to meet.
• Without having met J.R., Cally Harper never left her poor roots, and lives with an abusive husband in a shack. She finally takes a stand and shoots him dead, but will eventually go to jail for murder because no one would believe her husband beat her (according to what Adam tells J.R.).
• Without J.R. in the way and forcing him to be a part of the Ewing-Barnes rivalry, Cliff Barnes became a politician. When J.R. sees that Cliff has become Vice President of the United States, he tells Adam of its impossibility, that Cliff would ruin the country, and that he did not like the fact that Cliff would rise to his position of power. To make matters worse, Cliff becomes Acting President when the sitting President is disabled by a stroke. Adam goes on to tell J.R. that Cliff will become one of the great Presidents regardless of how he feels about it ("Nobody said you had to like it, J.R.," Adam specifically tells him).
• Since J.R. was never born (and thus never shot), Kristin Shepard never met him (and thus never died), and became a successful con artist in Los Angeles. She poses as a hooker initially and then a police officer, which sees her accept a bribe from an embarrassed customer.
• Having never met J.R., Sue Ellen has entered acting and become a successful soap opera star. Since Nicholas Pearce never met J.R. (and thus was never shoved out of the window to his death), he was able to form a relationship with Sue Ellen, who did not develop her alcohol problem that plagued her throughout her marriage.
• With J.R. out of the picture and Jock dying before he could find out, Ray Krebbs never knew of his Ewing blood ties. After an injury he suffered in a Ewing Oil-sponsored rodeo, Ray was forced to become a ranch hand and would often find himself out of work. Fortunately for Ray, however, he was able to have a great family life with a wife and children who loved him unconditionally, even if he could not always provide for them. One of his sons is named Jock.

After being taken through this journey, Adam tries to get J.R. to shoot himself. J.R. tells Adam he does not want to give Adam the satisfaction as he went back to Heaven. Adam then asks J.R. what made him think he was dispatched from Heaven and begins laughing demonically, revealing his true purpose. J.R. is immediately jolted awake in his bedroom while still holding the bourbon bottle and the revolver. He appears relieved that it was only a nightmare, but once again, Adam appears to J.R., this time in the bedroom mirror in a red suit. Adam is determined to have J.R. shoot himself, reminding him of reality for J.R. and the current state of his life and how better off everyone concerned would be. J.R. seems willing to oblige.

Meanwhile, Bobby has returned to Southfork for the night. J.R. does not hear him pull up or enter the house, as his focus is solely on Adam in his mirror. He slowly raises the gun to his head and cocks the hammer, and the frustrated Adam finally screams "Do it!" to J.R. with glowing red eyes. Bobby hears a gunshot and runs to the second floor to J.R.'s bedroom. As he reaches the doorway, he looks into the room and is horrified by what he sees, exclaiming "Oh, my God!". The episode concludes with a freeze frame shot of Bobby in the doorway, and the series ends with the fate of J.R. unknown.

Resolution

The "Conundrum" cliffhanger was not resolved until 1996, with the first Dallas reunion movie, Dallas: J.R. Returns. It was revealed in the beginning of the movie that J.R. had not, in fact, shot himself, but had instead shot at the mirror where Adam was appearing to him. The 2012 revival series did not acknowledge the reunion movie. However, when the revival series began, J.R. was still alive. According to the Dallas Facebook page, J.R. had indeed shot the mirror, but unlike the Reunion film, he didn't flee to Europe to recover.