Lucifer is describing his plan to Cain and mentions Abel is in hell, delighting Cain.

They need a new body to get Abel's soul to undo the original murder.

Pierce takes Lucifer with him instead of allowing him to go with Chloe. 

There is a little bit of a problem when Lucifer plops Abel's soul into the body of a young woman instead of the body of an old geezer, both about to perish. Even worse, Cain is still sporting the mark. They failed.

Charlotte is afraid to go to her hell to recover her memories even if that's what Linda recommends.

Lucifer and Maze share with Cain that Abel was the first soul in hell and demons learned how to torture by torturing him. His hell loop was Cain showing up to kill him again and again.

Abel also became multilingual and completely adaptable.

Dan and Chloe are looking for clues in the woods while she complains about training Lucifer into a great investigator and Pierce swooping in and taking him when a sniper beam fixes on Dan's forehead.

Oh, they found their culprit. His "threatening" letter to Alexa was that they're ALL gonna die. Some apocalypse bullshit. 

When Amenadiel catches up with Abel, he offers a solution by way of a handgun. 

Lucifer's solution to Cain, though, is that Abel has to kill him for their misery to stop.

Abel has no idea who Amenadiel is, but when she asks who he is and why he knows all of this, a gunman walks up behind Amenadiel gun drawn and Abel shoots. The guy splashes into the pool and Abel makes off just before Cain and Lucifer get to them. 

Amenadiel and Lucifer argue about father and what he has taken away and whether Lucifer should sit back and take father's abuse. Cain discovers the shot guy was a Bolivian cartel hitman who wanted to kill Bree.

Cain goes to Maze to help him find Abel. She says he always runs to booze or boobs, usually boobs. He figures since Abel has boobs, that might change his itinerary. Seconds later, the elevator door opens and Abel steps out, says hello to Cain and goodbye, shooting him in the chest.

Stuff happens, but it's not that interesting.

Maze and Amenadiel are arguing over the Linda thing. Literally, she is punching the shit out of him. But in the end, she decides not to throw the final punch and says he's ruining even that.

Charlotte takes what Abel says to heart and shares with Linda her hell loop. Her family is killed in front of her because she was a defense attorney.

Cain and Abel agree to accept each other's faults but stay out of each other's way. 

Lucifer breaks his agreement with Cain. Cain has hope as long as Abel is alive. Abel might be dead after being struck down in the street.