“The Blacklist” Season 4, episode 12 revolved around a heartbreaking love story and Red (James Spader) and Tom’s (Ryan Eggold) hunt for a criminal mastermind.

In “The Blacklist” Season 4, episode 12, titled “Natalie Luca,” a blond young woman (Elizabeth Lail) has the ability to kill people by kissing them, and one of her latest victims is Red’s accountant, Zack Smoll (Nick Reynolds). While Red’s associates believe that Smoll passed away due to a heart attack, he actually died of Luschen’s disease, an aggressive form of meningitis that can be contracted through minor physical contact and can kill its victims immediately. Red believes that his longtime rival, Baldur Magnusson (Daniel Davis), may have had something to do with the death of Smoll.

Red calls Magnusson to confront him about why he’s trying to wage a criminal war with him. His rival then replies that it doesn’t matter whether he really killed his accountant or not because the whole criminal world already believes he did, and Red not retaliating makes him look weak. “You have no choice but to come for me,” Magnusson says.

Red seeks out Tom to help him hunt down Magnusson, and they hatch up a plan involving a notorious assassin named Edgar Legat. Red tells Liz’s (Megan Boone) husband that Legat isn’t a real person, but an identity Red uses to cover up all the murders he and his associates have been responsible for. After hearing this, Tom assumes that Red wants to assume this identity and kill his longtime rival, but the latter has another plan in mind. He wants Tom to pretend to be the assassin, so he will be hired by Magnusson to kill Red. This way Tom will be able to lead Red to the criminal mastermind.

Their plan ultimately works out in the end, and Red finds himself face-to-face with Magnusson. His rival tells him that he did not have his accountant killed and that he only took advantage of the situation for his own financial gain. Red replies that it would have been easier for him had Magnusson turned out to be the killer because now he doesn’t know who is after him.

Meanwhile, in “The Blacklist” Season 4, episode 12, the Task Force is busy tracking down Natalie Luca after Aram (Amir Arison) discovers another death similar to Smoll’s. He also finds out that Luschen’s disease first known outbreak could be traced back to a Moldova family who were all killed by the deadly disease except for one daughter. The girl had apparently been taken to a local clinic first, but she was later taken in by Hawthorne Biologics and transported to Alexandria for treatment.

It turns out Natalie fell in love with a young researcher named Malik (RJ Brown), and they are now killing people and committing crimes in order to fund the latter’s research. The Task Force discovers that their objective isn’t to find a cure for Luschen’s disease, but to make Malik immune to it so he and Natalie can live normal life together.

Unfortunately, the pair doesn’t succeed in their to plan to target a poker tournament for the wealthy and get apprehended by the Task Force. When Hawthorne executives tries to kidnap Natalie, Malik also runs and tries to stop them by hitting the vehicle carrying her. During the mayhem that ensues, Malik gets shot by one of the Hawthorne people. But before he dies, Natalie kisses him for the first and last time.

“The Blacklist” Season 4, episode 13 is set to air on Thursday, Feb. 9 at 10 p.m. EST on NBC.