“The Blacklist” Season 4 shocked viewers when Red (James Spader) shot Mr. Kaplan (Susan Blommaert) in episode 2.

Red decided to get rid of Mr. Kaplan after they finally rescued her from Alexander Kirk (UIrich Thomsen). The two had been at odds since Reddington found out in the Season 3 finale that she helped Liz fake her death to get her family away from Red. She also knew too much about Red and his secrets so it was too big of a risk to let her live. However, in “The Blacklist” Season 4, episode 3, titled “Miles McGrath,” Mr. Kaplan proved that she won't go down easily.

Responding to a fan’s tweet about Mr. Kaplan’s fate, NBC teased on the series’ official Twitter account that she still has some unfinished business in “The Blacklist” Season 4. The tweet didn’t elaborate on what her “business” might be, but there’s no doubt that it will have something to do with Red, Liz and Agnes. After all, Mr. Kaplan betrayed Red last season in order to protect Liz, but her plan ultimately failed when Kirk found his daughter and granddaughter anyway. There’s also a chance that Mr. Kaplan might become Red’s foe in the future, since he has already proven that he’ll resort to any means to get rid of her.

“The Blacklist” executive producer Jon Bokenkamp previously opened up about Red shooting Mr. Kaplan. When asked about Red's reason for wanting to kill her, he told Entertainment Weekly, “Red values loyalty above all else, and Mr. Kaplan betrayed him in the most impossible way. Remember, Reddington killed Newton Phillips in Season 1 by suffocating him with a plastic bag from a funeral urn. He shot an old woman (Diane Fowler) after she betrayed him. Hell, he shot Pee Wee Herman! The man is ruthless. In Red’s mind, Mr. Kaplan had to go.”

Meanwhile, more details about Liz’s past were revealed in Thursday’s episode of “The Blacklist” Season 4. Liz found her mother’s (Lotte Verbeek) journal, which revealed that Katarina Rostova had once been assigned to Red and had fallen in love with him. This seemed to prove that Kirk may have been telling the truth when he said that Red and Katarina had an affair.

Kirk’s real motive for kidnapping Liz and her daughter Agnes was also revealed in the same episode. He’d already told Liz that he was dying, but he neglected to tell her that he had a rare blood disorder that afflicted the males of the Rostov family. Kirk also didn’t inform her that he had a chance to survive if he received transfusions from family members, and this is the reason why he won’t give up Agnes anytime soon.

Will Red and Liz finally manage to track down Kirk and rescue Agnes? Catch them when “The Blacklist” Season 4 airs on Thursday at 10 p.m. ET on NBC.

mr kaplan the blacklist Mr. Kaplan (Susan Blommaert) still has some unfinished business in "The Blacklist" Season 4. Photo: NBC