Timeless clip: The heroes meet JFK's rumored mistress

What happens in Vegas… could change history. In the third episode of Timeless, the team must travel to the Strip during the height of the Rat Pack era as they continue to chase Flynn (Goran Visnjic) through space and time.

There, they’ll encounter Judith Campbell (Elena Satine), who notoriously claimed she had been mistress to John F. Kennedy, Frank Sinatra, and Chicago mobster Sam Giancana. In the exclusive clip below, Lucy (Abigail Spencer), Rufus (Malcolm Barrett), and Wyatt (Matt Lanter) run into Campbell and try to offer her protection. She sees right through their cover — or rather, lie about being undercover — and doesn’t bristle at the knowledge that she could be in danger. “Lots of men want me,” she says. “They’re usually more polite about it.”

That gusto was the reason co-creator and EP Shawn Ryan wanted to feature Campbell for the episode. “People think history can be sort of dusty and boring, and one of our goals on this show has been to make history very alive and sexy and visceral,” he tells EW. “We just frankly started off with the idea of, ‘Can we do a real sexy episode in the past, and if so, what would that be?’ We started investigating the Rat Pack era of Las Vegas and who was hanging out then, and we came across the story of Judith Campbell, who was a very smart, beautiful young woman…. There’s a good argument to be made that if not for her, the connection between Kennedy and Giancana wouldn’t have been made, and Kennedy would not have won the election of 1960.”

Plus, time-traveling to Vegas in the 1960s posed a fun challenge for the production design team led by John Marcynuk. The crew not only populated a casino set with 50-year-old slot machines and blackjack tables, but also inserted a sleek 1963 Impala as a nod to Supernatural, which Timeless co-creator and EP Eric Kripke previously created. All the props, sleek sets, and costumed extras left even Marcynuk in awe. “I got lost in a sea of ’60s people,” he says. “I felt like a ghost, walking in the past. It was magical.”

Timeless airs Mondays at 10 p.m. ET on NBC.