5 things we now know about Ep. 1 of 'I Am Cait'

It's almost time for the premiere of I Am Cait, something you doubtless know (unless you somehow missed Caitlyn Jenner's 20/20 special, Vanity Fair cover or her ESPYs speech). In Los Angeles on Tuesday, reporters were invited to an advance screening of the first episode of the docu-series, which debuts Sunday on E! at 8 p.m ET. What did we learn? Well, lots.

1. While the show has Keeping Up roots, it's committed to giving back

I Am Cait opens on Caitlyn, awake at 4 a.m., fretting about how this will all be received. "What a responsibility," she says, of suddenly being a transgender spokesperson, particularly for those at risk. "I just hope I get it right." Later she takes an incognito trip (aka in three cars to avoid paparazzi) to San Diego to meet with the parents of a transgender child who took his own life. (Contact information for the Trevor Project Lifeline also follows each broadcast.)

2. Mom plays a big role

Esther Jenner plays a pivotal role in the first episode of I Am Cait, visiting her child's Malibu pad and seeing Caitlyn, formerly Bruce, in full dress for the first time. "I think he's a very good looking woman. And he's still Bruce. It's a lot of getting used to. But I will," she tells producers in an emotional interview.

3. Kim and Kanye guest star, obviously.

E! wasn't born yesterday, OK? The longtime TV home of the Kardashians and Jenners knows that when you have reality gold, use it. And so, Kim and Kanye stop by Caitlyn's house in the first episode. "What up!" says Kanye, looking uncharacteristically cheerful. This is by far the funniest segment in the show, and includes Caitlyn's sister quizzing Kanye on his white kicks and Kim going through Caitlyn's suddenly-designer closet. (Just wait until you see which dress she and Kris both bought.)

4. Kylie gives Caitlyn a makeover

In the form of teal extensions.

5. Caitlyn plays tennis!

"Now I know why girls need a sports bra," she cracks on the court with her sister.