Cristin Milioti, Josh Radnor

"Tango! You're tangoing!" The photographer at TV Guide Magazine's cover shoot encourages Josh Radnor and Cristin Milioti to unleash their inner Latin groove. They laugh. Dip. Embrace. Lock eyes. Spin. Entwine legs. Almost fall. Hold each other up. Just like the loving goofball soul mates they play on How I Met Your Mother — idealistic architect Ted Mosby and his future bride, still known only as the Mother.

The small audience of makeup artists and photo assistants breaks into impromptu applause as the photographer shouts, "Great! You're done!" Milioti looks surprised: "We are?"

Sadly, it's true. After nine seasons, the genre-stretching sitcom about a guy looking for his one true love will have its last dance in an hour-long farewell on March 31.

For Radnor, this final season has been extremely gratifying. Though Ted hasn't officially met the Mother, flash-forwards have shown many happy milestones in his life with the woman fans first glimpsed in the Season 8 finale. ("I had a moment of panic when I realized how important the role was!" confesses Milioti.)

"One of the things that kept me going when I got knocked around and heartbroken for nine years," Radnor says, "was knowing the whole thing was rigged to give Ted a romantic victory in the end."

That victory was hard-won. Let's see: There was the time dermatologist Stella (Sarah Chalke) left him at the altar and the second time he thought baker Victoria (Ashley Williams) was "the one." Not to mention the parade of crushes and bad dates, which included randy receptionist Abby (Britney Spears) and Slutty Pumpkin (Katie Holmes), to name a few. And, of course, there was his longtime love for journalist pal Robin (Cobie Smulders), who is marrying Ted's suave best friend, Barney (Neil Patrick Harris).

Their wedding weekend at the Farhampton Inn has been the focus of the current season. And, so far, it's been 56 hours of hilarity — with the occa­sional drama: Ted finally let go of his feelings for Robin; matron of honor and spunky art lover Lily (Alyson Hannigan) and her husband, Ted's sensitive college roommate, lawyer Marshall (Jason Segel), fought and then made up; Barney got drunk; etc.

The finale "picks up right after Barney and Robin's wedding and becomes this time machine that takes us into the future," teases executive producer Craig Thomas, who created the show with college friend Carter Bays. "It tells the story of the 17 years between May 2013 and 2030, complete with many ups and downs."

Stated more simply: "It's a doozy," says Hannigan, sitting in the gang's well-worn booth at MacLaren's on Fox's Stage 22, where HIMYM has shot for nine seasons. "I'm really going to miss everyone."

At the last table read, held on Valentine's Day ("Just rip my heart out," Hannigan says of the scheduling), the cast went over the script for the series ender, and there were waterworks. "We were just shy of solving California's historic drought," says Thomas.

Though details from the big finale remain top secret, we do know the hour will include a brief appearance by a beloved guest star. "A fun, random one from the past," Thomas hints. It also might feature a robot in a tuxedo; a scene at that fateful Farhampton train station; the moment that Ted and the Mother first meet; and, finally, her name. "The very end of the episode — the last two minutes of it — is exactly what we'd planned out years ago," Thomas says. "We even shot a part of the last sequence back in 2006 with Ted's kids, before they became the adults they are now."

For more on How I Met Your Mother, pick up this week's issue of TV Guide Magazine, on newsstands Thursday, March 20!

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