It's just another Monday at Brevet Investments until the bloodied body of Elena Brevet is found in the supply room. She was raped, beaten and repeatedly stabbed; and her throat was cut. The medical examiner estimates she died at least 48 hours before, which is consistent with her being last seen alive on Friday night.
Elena owns Brevet Investments with her husband, Jason. He had flown to Miami on Friday night for business, and was due back Sunday. When Elliot and Olivia go to the Brevet house, they find Jason bound to a living room armchair, dead about 12 hours from a slashed throat.
A monogrammed keyring on the table indicates Jason's killer took Elena's keys to get into the house. Upstairs is an empty built-in safe. It's a totally pick-proof model, meaning the killer got the combination by torturing it out of Jason. A new tool called a gas chromatograph indicates the safe had contained at least $1 million in cash.
The Brevets had been heavily in debt, and their company turns out to be just a high-end pyramid scheme. Their real business was laundering Colombian drug money, particularly for a bogus client called Casa Vega Enterprises. The Brevets skimmed the cash in the safe, and the dealer found out and killed them.
SVU consults Narcotics detective Miguel Sandoval, who recognizes the laundering scheme. A Colombian drug dealer in Bogota is in the money in New York, but he can't move all that cash out of the US without attracting attention. So dealer hires black market money broker, who finds Colombian nationals with checking accounts in the US. These good people write clean checks in exchange for the drug cash, keeping a bit for their trouble. The dealer can deposit these checks anywhere, such as into the Casa Vega account at Brevet Investments. Then the money can be legitimately wired to Colombia.
One of the Casa Vega check writers is a woman whose son Miguel sent to prison for selling marijuana out of the family business. Miguel, Elliot and Olivia pay her a visit and offer to transfer her son to a facility closer to home, if she helps them. She points them to a man named Felix Montoya.
At Montoya's apartment the detectives find Felix and his wife dead in the living room, shot execution-style only a short time before. In a bedroom is their young son Antonio, who's also been shot through a pillow covering his face. However, the shooter missed and only grazed the boy's skull. In the hospital, Antonio says a ghost shot him and his parents. Outraged that any drug dealer would shoot a child in the head, Miguel insists on participating in the investigation.
Ballistics tests reveal something unexpected: the weapon used to shoot the Montoyas was also used to shoot former SVU prosecutor Alexandra Cabot two years ago. A Colombian drug dealer targeted Alex when she persisted in prosecuting one of his men for raping and murdering an undercover NYPD officer. (Season 5's "Loss". Officially Alex is dead, but only Elliot and Olivia know she's actually alive and hiding in witness protection.)
The DEA runs the entire cast of Casa Vega characters through its HIDTA computer, which searches for links between cases. However, no one connects back to the drug cartel. When Miguel then comments "This guy really is a ghost", the HIDTA technician recognizes their killer as El Fantasma ("the ghost" in Spanish), aka Liam Connors. Connors is a former IRA hit man who became unemployed after the cease-fire in Northern Ireland. Now he and others like him are in Colombia working for the cartels.
Through a parking ticket on a rental car, Connors is eventually tracked down and arrested. The grand jury indicts Connors for the Brevet and Montoya murders, but not within the legal deadline for either indicting him, or releasing him until his trial. To keep Connors in custody, Casey orders Elliot and Olivia to arrest him for Alex Cabot's murder. The detectives hadn't expected that, and now they're in a major jam. Since Alex is alive, they've just charged Connors with a crime he didn't commit.
Captain Cragen gets a visit from Jack Hammond, the DEA agent in charge of the undercover drug operation from two years ago. Hammond raises holy hell over Connors' arrest for Alex's murder, then realizes Cragen didn't know Alex is alive. Cragen is furious with Elliot and Olivia, who've now jeopardized everything they've worked for and every case they've worked on. Casey isn't happy either, because she's on the hot seat with the judge for charging Connors with a crime he didn't commit.
Cragen and Hammond visit Alex at her home in Wisconsin, and show her a picture of Liam Connors. The person she's lived in fear of for two years, finally has a face and a name. Hammond apologizes that they can't prosecute Connors for Alex's shooting, but at least they've got him for the other four murders and the attempt on Antonio Montoya. But Alex wants Connors to pay for what he did to her, too. And the other cases depend entirely on young Antonio's testimony. As a prosecutor, Alex encouraged countless victims to stand up and face their attackers. Now it's her turn to do the same.
Alex returns to New York to testify, even though it means revealing she's alive and becoming a target again. With Alex's presence, Casey manages to keep Connors in custody, and to save Elliot and Olivia's professional necks. At the trial, on cross-examination Connors' attorney asks Alex only one question: Did you see Liam Connors shoot you? The answer is no, but Alex is able to goad Connors into blurting out in court, "You think you're safe? They know where you are! You should have stayed dead!"
The jury convicts Connors on all counts of murder and attempted murder. Cragen, the detectives and Casey gather in Casey's office for a victory party. When they hear someone else coming, they think it's Alex and quiet down to surprise her. The door opens and Hammond comes in, alone. He apologetically tells them that Alex and Antonio Montoya are being moved to new identities, and she had asked him to say goodbye for her.