Goran Visnjic Goran Visnjic

Poor Kate. It's difficult to juggle a love life when you're a jet-setting stewardess and undercover spy. Luckily, Goran Visnjic, who once played Dr. Luka Kovac on ER, has the remedy for Pan Am's lovelorn flight attendant.

Beginning Sunday (10/9c on ABC), Visnjic will play debonair Yugoslavian diplomat Niko Lonza, who takes a personal interest in Kate (Kelli Garner) on a flight from New York to Monte Carlo. The precocious redhead has had a hard time of it lately; the CIA put her on notice for disobeying orders and her younger sister Laura (Margot Robbie) moved out. It's perfect timing to begin a new, ego-boosting relationship, even if it doesn't begin in the most romantic way.

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"Just before she gets on the plane, she gets this assignment," Visnjic tells TVGuide.com. "Her CIA handler gives her a photo of Niko and he tells her, 'This is the guy who's going to help you get inside that casino in Monte Carlo, but he can't know what's going on. You just need to befriend him and use him to get inside this casino.'"

Once Kate finishes her assignment, she finds Niko again and begins their love affair in earnest, without orders this time. "She thinks that she's no longer putting Niko in any kind of danger from the CIA since he wasn't part of the actual assignment, but just a tool to get inside the casino," explains Visnjic. "That's why she thinks it's OK to fall in love with this guy because the CIA is apparently not interested in him."

Politically, Kate shouldn't have had anything to worry about by getting involved with Niko. Visnjic says, "[The writers] wanted to bring a character in who was going to be from a communist country in 1963, but also politically neutral because Yugoslavia at the time was not part of the Iron Curtain. He works in the UN and lives in New York."

As their relationship deepens over the course of a four-episode arc, they enjoy intimate interludes as well as light-hearted dates, such as one outing at an amusement park. "That was in an episode when they get back from Monte Carlo," Visnjic says. "You believe that these two people might have a beautiful future ahead of them."

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Unfortunately, Kate is new to the spy business and doesn't actually know the deeper game at stake. "Right after that, something hits the fan and all hell breaks loose for them," says Visnjic. "The CIA gets involved with their relationship and also the Yugoslavian Secret Service. It gets really political and this love story turns into a spy story. It's quite intricate. Things are never as simple as they look."

The actor doesn't go into detail, but apparently Niko and Kate aren't destined to take a Pan Am flight on their honeymoon anytime soon. "I can't tell you much, but it's an interesting ending, a story of betrayal and a love story," says Visnjic. "It's not going to end well." Poor Kate.

Pan Am airs on Sundays at 10/9c on ABC.

Are you psyched to see Goran Visnjic back on TV? How are you liking the espionage aspect of Pan Am? Why can't Kate just be happy?