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What Happened to Detective Jace on The Irrational? The Tragic Cliffhanger, Explained

Marisa and Jace's love story has seemed promising but, the events of The Irrational Episode 10 may end their happiness for good.

By Joe Dziemianowicz

“All gave some. Some gave all.”  

How to Watch

Watch The Irrational Mondays at 10/9c on NBC and next day on Peacock

Tragically, that’s the epitaph for Detective Jace Richards (Brian King). His dogged digging into a fatal 20-year-old bombing that left behavioral scientist Alec Mercer (Jesse L. Martin) scarred led to Jace’s murder on The Irrational.

The NBC series’ penultimate episode ended with Alec's ex-wife, FBI Agent Marisa Clark (Maahra Hill, coming home, eager to talk with Jace about his new theory on the church bombing case, which killed 13 people. Marisa and Jace began dating while working together to investigate who was really behind the murders at the church. 

Tragically, Marisa found Jace shot on the floor of her home. She urgently called for help, telling dispatch, “Agent down!” But it was too late for Jace.

What happened to Jace on The Irrational?

Unfortunately, Jace was shot to death on The Irrational Season 1, Episode 10. In the finale, we learned why he had been murdered — and by who.

Marisa and Jace had determined that Wes Banning, who was incarcerated for the bombing, built the explosive in the church case. Peter Shelby, a member of a fundamentalist group, then detonated the bomb. Both men, who recently ended up dead, worked for a mastermind who used the alias of Mathias.  

RELATED: Everything We Know About The Irrational Season 2

Jace and Marisa considered that Mathias was Senator Sanford, who’d used the church explosion to his advantage 20 years ago — he had been behind in the polls, but received public sympathy after the attack, which occurred at a place where he had just had a campaign event and affected some of his staffers.

 Following Jace’s murder, Marisa zeroed in on Sanford as the prime suspect.

Jace Richards uses a phone in his car in The Irrational Episode 110.

“That bomb happened at his event,” Marisa said. “Jace goes poking around him, and two days later he’s dead.” 

As Marisa came to suspect that Mathias worked inside the FBI, she discovered her home was bugged: Someone “had ears” on everything she and Jace discussed. Could this have led to his death?

Mercer’s team also learned that two decades earlier, Sanford was involved with several young women on his staff. One of them overdosed during a campaign function — and it seemed he used the bombing to cover up her death.

Investigators then discovered that Sanford earned a Purple Heart saving his team in combat in Somalia. One of those team members was Mathias. With military training, he had the skills to kill Banning and Shelby.

“And Jace,” said Marisa. “He didn’t stand a chance.” 

An old photo of Sanford’s war buddies led Marisa to a shocking conclusion: FBI Head of Intelligence Bob Caswith is Mathias. To repay his debt to Sanford, he reasoned that it was OK to kill, explained Mercer.  

“It all makes sense now,” said Marisa. “How Mathias manipulated Wes Banning for all those years. How he found Wes’ daughter. Jace wouldn't have thought twice about letting Bob in. He trusted him.” 

Senator Kevin Sanford appears in the dark in The Irrational Episode 111.

To prove that he is Mathias, Marisa and Alec lured Caswith to a public meeting with an email supposedly from Sanford.

“I can’t understand how you could murder Jace,” said Marisa during the encounter. “He was one of us. You knew that he was only looking into this case because of me. You could have just killed me.” 

Caswith lowered his weapon, presumably understanding Marisa was right, but he was killed by Sanford, who claimed he had nothing to do with the bombing. However, Alec later got Sanford to implicate himself with a secret hot mic, leading to the end of the bombing saga.

There’s finally a resolution, but it was too late for Jace. Marisa needs to now spend time getting over Jace's death — as she works on her friendship with her ex-husband, Alec.

Catch up with The Irrational now on Peacock as we wait for answers with Season 2. 

Originally published Feb 12, 2024.