NBC's relationship comedy "A to Z" will answer a question TV fans never even thought to ask: Do Cristin Milioti (the Mother on "How I Met Your Mother") and Ben Feldman (Ginsberg on "Mad Men") have chemistry? That, and the conceit of following a relationship from beginning to end over the course of a single season, were the hot topics at the show's panel at the TCA 2014 summer press tour.

Executive producer Ben Queen (a writer on "Cars 2" and creator of that short-lived Fox series "Drive" with Nathan Fillion and Emma Stone) said chemistry was the primary concern in casting. "When they got together to do the network test they had met each other literally a hour before. It was real electric chemistry. I had been told this existed and it's there," Queen said.

While Feldman was more self-effacing ("Cristin had her job, they needed to bring in a guy who wasn't going to screw up opposite her..."), Milioti agreed with Queen that there's no faking the c-word. "You know the minute when it's right, either in life or in front of 20 executives with notepads," Milioti said. "Either it's there or it's not. It's not tangible, it's not something you can manufacture."

The pilot opens and closes with voiceover narration from actress Katey Sagal informing the audience that the season will follow the relationship of Andrew (Feldman) and Zelda (Milioti) from beginning to end. But the producers were coy about whether or not that means the couple is destined to separate.

"There will be an ending, by ending we mean a change," said executive producer Rashida Jones, hinting that the change could be a break-up or it could be moving to "the next level." "Relationships change all the time. Our hope is to put the ticking clock on it will help people to invest in whatever that change is."

Queen added that each episode will tackle a different phase in the main couple's courtship as represented by a different letter of the alphabet (any similarities to "Sesame Street" are presumably unintentional). "I think it's a good organizational structure for a season," Queen explained. "The next season can do that for another aspect of a relationship."

With both leads coming off memorable recent TV gigs, it was inevitable they'd face a few questions about those jobs. When one reporter asked if "the end of the relationship" might mean one of the characters dies, Milioti quickly quipped "We've played that card, I believe."

Feldman said his casting happened to fit in perfectly with his "Mad Men" exit. "I just got really lucky timing wise," he said. "[My last] episode of 'Mad Men' aired the night before the NBC upfronts. We were going to do interviews on the red carpet the next morning and I turned to my publicist and said, 'I just want to warn you, I know you haven't watched the show but it's going to be a lot of nipple questions.'"