(CBS News) -- We saw the boots, the yellow umbrella and even a glimpse of her face during the season 8 finale, but starting tonight (Monday, Sept. 23), viewers will get at closer look at the mother (actress Cristin Milioti) when CBS' "How I Met Your Mother" returns for its ninth and final season.
This season takes place over the course of Barney (Neil Patrick Harris) and Robin's (Cobie Smulders) wedding weekend in "Farhampton," Long Island -- while each member of the gang is on the verge of some big changes. Ted (Josh Radnor) is about to move to Chicago, Marshall (Jason Segel) and Lily (Alyson Hannigan) are gearing up to move to Rome for Lily's job, and Robin and Barney are about to exchange vows. It's all narrated through flashbacks from the future.
In tonight's two-part, one-hour premiere, dubbed "The Locket" and "Coming Back," Marshall sees something online that makes him change course, while his wife, Lily, talks to Ted about finally letting go of Robin. Sherri Shepherd ("The View") guest stars as Daphne, a woman on the same flight as Marshall; Wayne Brady returns as Barney's brother, James; and Roger Bart ("Desperate Housewives") guest stars as Curtis, a hotel clerk.
Ellie Kemper of "The Office" fame will also play a role in the upcoming season, as Cassie. Thomas told TVLine that Cassie will also be at the nuptials as "one of the most attractive, available, and -- as Ted discovers -- unfortunate guests at Barney and Robin's wedding."
"How I Met Your Mother" airs Monday nights this fall at 8 p.m. ET.