Gene's timeline. Black & White. Omaha, Nebraska. It is cold outside. Gene waits in a phone booth. He calls Francesca. We learn that the attorney's business card Jimmy gave her was that of Bill Oakley (cf. S4E5 'Quite a Ride'). It is implied that he quit his job as district attorney to open his private practice.
Albuquerque. Francesca is looking around her, fearing to be watched. She holds a mobile phone in her other hand. Kim picks up.
Gene thanks Kim for calling on his anniversary date as they convened. Kim doesn't say a word. (The camera doesn't show her face during the call.) He says that although they have not spoken much these last years, he has been thinking a lot about her. (It is implied that Kim disappeared after Gus's death as the DEA started to investigate Madrigal.) Kim seems disillusioned. Gene at the end of the call even suggests that they reunite. But Kim won't disclose her location, she says she needs to go. Phone hangs up.
Gene is a bit shaken up. The only person he truly cared about is now out of reach forever...
Montage. Gene still has a slight hope. We see him sending dating ads in different newspapers, targeting each state. He uses information that only Kim and him would know, mentioning Viktor (the name that he chooses to con people) and Zafiro Añejo in the text, hoping she would try to contact him again.
He receives some calls from random women, but not Kim. He becomes more and more jaded with life and lonely. At one time, we see in the news that the Sandpiper Crossings was settled, but the irony is that Gene cannot claim back his part of the money, and he gets irritated when he sees a flamboyant Howard on TV.
Back to where we left off at the end of the S5 teaser. Gene was recognised as Saul Goodman by Jeff, the cab driver. He starts thinking about ways to deal with the situation. What are his motives? Is he trying to blackmail him?
Gene does not have much choice. He is in an eat-or-be eaten situation. He better makes the first move. He calls the number he was given and asks for Jeff.
Gene meets with Jeff in his car; Jeff greets him but everything about him seems fake. Gene asks him what he really wants. Jeff eludes the question, he says he is an admirer, he just wanted to hang out in person with Saul. However, Gene sees through his game and he contradicts him.
Silence. Jeff looks at Gene with his piercing gaze and asks for a large sum of money. Gene: 'And you leave me alone? No more hearing from you, right?' Jeff accepts.
Back at home, Gene starts panting. He is not made for this anymore. He looks at the diamonds. They are still there. He removes his coat and we see... a recording device. He was recording his discussion with Jeff all this time! (Thank you Chuck for the idea.)
Gene meets with Jeff and his friend in a basketball field. Jeff is surprised when he learns that Gene has not brought the money and that he threatens him to send the tape of their discussion he recorded to the police. If he ever decides to report him to the police, they would be both in trouble.
Jeff's friend grabs Gen by the collar. But Jeff tells his friend that there is no need to be violent. Jeff mentions that he knows a million ways to make Gene's life miserable. They do know where he works... Jeff gives him an ultimatum. He has one day to change his mind.
Gene starts having dark ideas. He can't sleep. He calls in sick for his job. He doesn't have much choice: he needs to disappear again or get rid of the problem from the root, even its means resorting to a radical solution...
Next morning, he looks out his window to see if someone is watching him, then goes to buy a revolver from a shady gun seller. He drives to the Omaha United Cabs offices and manages to get Jeff's address by telling a fake story to the secretary.
Gen drives there, with his gun hidden. He switches off the light of his car and sits there, waiting for Jeff. His head is buzzing with a million ideas.
Then he feels bad, like really bad. He isn't a killer, he is Jimmy. Gene just leaves and gets rid of the gun.
He stays at home, thinking about the deadline set by Jeff and his buddy. He looks at his ceiling the whole night. Deep down, he thinks, 'Fuck it! What are they gonna do?'; however, he can't help but dread the next day.
Next morning, he goes to work, his stomach churning. Everything goes fine until police officers come to him. One employee is pointing at him. Gene's heart starts beating fast...
The police officers ask him to follow him. This is a walk of shame. They show him... a big tag written on one of the walls: 'Gene Takovic is SG'. The officers interrogate him on the meaning of this tag and who might have written it.
He manages to find some random excuse: maybe an angry customer or a prankster. And for the meaning of SG, well maybe it means 'so great' or something similar. The police officers are still intrigued and don't know what to make of this.
The situation has gotten out of hand. He is now in a corner. He goes to the bathroom, has a panic attack. He calls Jeff, the cab. Jeff tells him that he warned him and that he is not afraid of his threat to send the recording to the police, as he knows he has more to lose than him. At the end of the call, Gene capitulates, he will give him the money he asked for.
He looks at himself in the mirror. Something doesn't sit right with him. It feels so unlike him to give up that easily. He keeps looking at his reflection. Then weirdly enough he feels the old energy that he has repressed all this time. He is not afraid anymore of saying out loud this truth: 'I am Saul Goodman, so what?' (This is a call-back to the bathroom scene in the pilot.)
When he leaves the bathroom, we see that Gene made up his mind. But he has not defined his strategy yet. Back at home, he starts thinking but without much success. He is running out of inspiration and decides to play his old cassette video of Saul... He has an epiphany...
He sees the time; he gets up suddenly. He goes to the supermarket which is about to close; he rushes to buy what looks like paper and video equipment.
Back again at home, he sets up a camera... and puts a chair in front of it. We don't see the rest of the operation, but we know that he is preparing something. We hear for the first time as he is working on his last shenanigan.
Next morning, we see Jimmy dropping letters. He also gets rid of all his belongings and Saul Goodman video cassettes.
At the time of the meeting with Jeff and his friend, Gene is a bit playful. He gives Jeff the money (he sold off-screen the diamonds). Once the deal is made, Gene shows that he has been wearing a microphone. Then police show up to catch Jeff and his friend. (We understand that Gene called the police prior to the meeting to notify them that he was being blackmailed.)
Gene is waiting in an interrogation room alone; he is serene. Then a police officer shows up, he says there is an inconsistency in his story. Gene mentioned before that he was blackmailed for selling fetish videos of himself sitting on pies (a made-up excuse that Jimmy used to defend Daniel Wormald in S2E2) whereas Jeff claims that Gene is a fugitive.
The police officer has a print of Jimmy's photo. He asks him if his real identity is Jimmy McGill. Gene takes a deep breath then asks for a lawyer. He is put under arrest.
Change of scenery. We see... a bored Kim working in a video store. She has a different look: she is wearing glasses and her hair is shorter. She is recommending a movie to a customer.
Then, she just freezes when she sees the television. The reporters announce a breaking news: Saul Goodman's arrest. Then, Gene appears on the screen in what seems like a recorded confession. He admits being Saul Goodman and he confesses to having done wrong things in the past. He lived in fear for so long and now it is time for him to redeem himself. He is sorry for all the people he hurt. He is now ready to face the music of all of it. (Gene recorded his confession and sent it to media outlets, knowing he would be arrested after defeating Jeff. He decided to turn himself in after he realised that facing the consequences of his actions was the only way to lift the remorse and guilt he was living with all these years.)
Kim stays speechless. She feels that the confession was sincere and it made her reminisce of the man she used to know. Right after, the reporter interviews Ernesto.
A few weeks passed. We see Kim arriving in Albuquerque by train. She feels like a complete stranger in the city. She takes a cab and goes to the state prison to meet with Jimmy. When he sees her, he starts to cry... He wasn't ready to see her as she used her fake name to come to the visit.
Jimmy appears to be doing pretty well in prison. He seems to 'game' the system and have good relationships with other inmates who benefit from his law knowledge.
Kim explains that a lot of things separated them in the past. However, despite that, she missed his cheery presence and the good time they had. She reassures him that she knows that he is a good man inside, despite all what has been said, and admires his courage.
She always feels that he is the only one with whom she was her true self. Jimmy asked her if she made her new life with someone else. Kim refuses to answer: she is here to speak to him as Kim as a friend, not a lover.
They hold their hands amicably. Jimmy asks her if he will see her again. Kim pauses before replying: she is ready to help him as much as he can. Jimmy sees her leave.
He goes back to the prison cell which is dark and dull. Light passes through the window, suggesting that there is a gleam of hope. He lies down on the bed. Close up to his face. For a few seconds, he is reliving, he smiles, he feels peaceful. (This is reminiscent of the ending of Once Upon a Time in America.) Is he dreaming? Will he see Kim again? ENDING.
TL; DR: In the post-Breaking Bad timeline, Gene defeats Jeff, the cab driver who was trying to extort him, but he is caught by the police (as part of his plan). Kim who lost contact with Jimmy visits him in jail and they reconcile. Jimmy is now ready to face justice.