The role reversed in "The Pavlovich Brothers," episode 19 of "The Blacklist," when Tom warned Liz that Red is not what he claims to be. Previously, it was Red who had kept warning Liz that she should be wary of her husband. The difference is that Red warning came without evidence to back it up, while Tom has a box containing evidence against Red.
The photographs that Liz found in the box at the end of the episode might be related to her father's death. In one of the previous episodes, Red had suffocated her father with a pillow, putting an end to his life. Liz's father was dying and had wanted to tell Liz about Red and how they are related. Red had killed him to stop him from spilling secrets. At the time, Red had met Tom inside the premises of the hospital. It is very much likely that Tom had seen Red killing Liz's father and had clicked the pictures.
Liz has started to trust Red despite knowing that he is not the good man. This revelation is set to shake her up. In the preview clip of episode 20, "The Kingmaker," Liz can be seen telling Red, "we're done, you're a monster."
Meanwhile, Red will also find himself under-attack from the most feared blacklister of all. The preview of the episode suggests that this blacklister will target his interests and allies. The preview clip says that "Red's world is crumbling." Red has always found a way to wriggle out of a difficult situation and he is very much capable of fixing things. It will be interesting to see how he does that in this episode.
Linus Roache has been roped in to play the role of the Kingmaker. Talking about his role, Roache said to Hitfix "... this is a man who thinks he makes kings, so I suppose that's an even more powerful position to have. A king is a still vulnerable, because he's visible and seen and the structures around him have been taken down, but a man who goes around making kings? He can't be seen."
Official Synopsis of "The Blacklist," Episode 20, "The Kingmaker":
"After a Politician in Prague is framed for a murder, Red suspects it's the work of The Kingmaker -- a strategist behind the rise of some of the world's most powerful politicians. While Red helps Liz and the FBI catch him, Liz uncovers a secret that Red's been keeping from."