Nygma (Cory Michael Smith) is closing in on Isabella's (guest star Chelsea Spack) executioner in the upcoming episode of "Gotham." Does he really believe the culprit is Butch (Drew Powell) and not Penguin (Robin Lord Taylor)?

In the episode titled "Mad City: Time Bomb," the synopsis (as per CarterMatt) reveals that Nygma is out to get revenge for the death of his love interest. Isabella reminded him so much of Kringle that he could not help but fall for her. In the past episode, viewers saw Penguin plotting to kill her. He was jealous of Isabella because Nygma was spending a lot of time with her and not with him. When she suddenly went missing, Nygma told Penguin about his suspicions that Butch murdered her.

When Penguin started to show Nygma more attention than necessary, Butch got angry. He had been the other man's sidekick for so long that he could not accept the fact that someone else would take his place. In a brilliant maneuver, Nygma made it look like Butch was betraying Penguin. The scheme worked, since Penguin transferred his loyalty to him and sent Butch away. Nygma cannot wait to kill Butch, since he knows his true colors. Before they parted, he told Butch that he planned to kill Penguin himself.

On the other hand, Nygma's accusation against Butch may be a ruse to make Penguin think he is not onto him. He knows someone with power has ordered Isabella's death. Nygma may just be waiting for the right time to trap Penguin and make him admit to the murder.

Meanwhile, the promo reveals that Falcone (guest star John Doman) will ask Jim (Ben McKenzie) for help when unidentified men try to kill Mario (guest star James Carpinello). His son will be attacked on the eve of the rehearsal dinner of his wedding to Lee (Morena Baccarin).

"Gotham" season 3 airs Mondays at 8 p.m. EST on Fox.