Eddie Morra's charade can only go on for so long.

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The original Limitless protagonist, Bradley Copper's Morra is moving into dangerous territory. What's worse, the FBI may soon be on to his little secret. It's Brian's (Jake McDorman) job to keep the Bureau off the senator's case, but even with a dose of NZT, the consultant will have a hard time keeping Rebecca (Jennifer Carpenter) from the truth.

"That's something that starts to get really scary for Brian: she's moving in a direction he knows is dangerous, and he's not really privy to all of the information," McDorman told TV Insider in the wake of Tuesday's episode. "She's just connecting the dots as she does, and as she does well. This is the first time the question is said out loud: 'What if the senator is on NZT?' That is the big red button of the entire show."

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It sounds like Morra should watch his back, particularly considering that Brain is no longer following his instructions to the letter. Piper is still out in the world, and now Copper's character is facing threats from more than one location.

"Whenever [Piper] feels she's primed and ready to make a second attempt on his life; if she doesn't succeed, he's going to be in a lot of trouble," McDorman warned. "I think it's incredibly unsettling."

Limitless airs Tuesdays at 10 p.m. ET on CBS. Click the video below to see a preview for the series' latest episode, "The Assassination of Eddie Morra."