Andi...I'm not your sister. I'm your mother.

Bex to Andi

13 is the first episode in Season 1 of Andi Mack. It first aired on April 7, 2017 to 1.24 million viewers.



Andi's world turns upside down when her older sister, Bex, returns home on her 13th birthday and reveals a family secret.[1]

Full Plot

Buffy and Cyrus are walking down the street when a motorbike stops abruptly next to them. They freak out and yell at the motorist for being reckless. The motorist then takes off the helmet. It's their friend, Andi Mack.

Andi explains that she got the motorcycle without asking her mother, Celia because she is turning 13 and becoming a teenager tomorrow. And that means she gets to rebel. When the gang arrives at Andi's driveway, Andi chickens out and asks if Cyrus could hide the motorcycle so that Celia doesn't find out.

Suddenly, another motorcycle comes at full speed towards the driveway. Andi recognizes the motorist. It's her cool older sister, Bex. Bex has been travelling all over the world. She rarely comes to visit. But now she's here. For Andi's birthday. Andi jumps to hug Bex and reintroduces her friends, Cyrus and Buffy to Bex who still remembers them. When Bex asks about Andi's motorbike, Andi asks Cyrus to say that it's his. Cyrus takes the bike with him. Bex tells Andi that she came as a surprise and Andi is worried that their mom won't like it because she hates surprises. Andi and Bex walk into the house and Cyrus and Buffy leave.

While, Bex's father, Ham is excited to see Bex home, their mother Celia is not too happy about it. Bex tells them that she is finally ready to settle down but Celia is not impressed. Andi reveals that they've already turned Bex's room into a gym but Bex is willing to handle it.

In Andi's room, Bex and Andi catch up about all the time they haven't been together. Andi impresses Bex with all the bracelets she's made and how she can turn pretty much anything into a bracelet. She also shows Bex all the scarfs Bex used to send to her from different places and how she's turned them into amazing art. Andi mentions one from a music festival where people supposedly get naked and asks Bex if she ever got naked. Bex assures Andi that she know her better than that. But does she? Does she really know Bex? She wonders. Bex feels compelled to show Andi her memory box where she keeps her old photos. Celia doesn't like the idea of showing the memory box because it contains family secrets that Andi is not ready for. Bex takes the box to Andi anyway. The sisters go through Bex's photos. Meanwhile notices a picture of a boy on Andi's computer. Andi says that the boy is Jonah Beck and she has a crush on him. Bex leaves the room. Andi is left looking at her photo of Jonah Beck.

On Andi's birthday, Bex takes Andi down to the sports field and says she's got a surprise birthday present for her. They spot Jonah Beck running towards them. Bex says that her birthday present is getting Jonah Beck to train Andi Mack how to play frisbee. Andi doesn't like the idea because she gets so nervous around Jonah Beck. But Bex insists that this is a good chance for Andi to spend more time with her crush. Jonah Beck arrives and after an awkward introduction, the frisbee training begins. Jonah and Andi have a lot of fun playing frisbee while Bex takes photos of them. Jonah is impressed by Andi and asks her to join his frisbee team.

It's all fun until... AMBER ALERT! Amber arrives and introduces herself as Jonah Beck's girlfriend. Andi doesn't recognize her because she goes to Grant High School while Andi and Jonah are still in Jefferson Middle School. Andi freaks out and starts to leave. But first, she confidently tells Amber that introducing herself with "Amber Alert" is not cute. Amber alerts are for kidnapped children.

Andi confronts Bex for making her play with Jonah Beck who has a high school girlfriend. She runs into her room and Bex follows her to apologize. Andi tells Bex that she will never get to be as cool as her. She will never get to be in Bex's memory box. Bex acknowledges that she made a mistake. In fact she's made a lot of mistakes since Andi was born. This scares Andi a little as she notices that the tone is turning to something serious. Bex tells Andi that she is in the memory box too. She brings over the memory box and takes out a photo concealed in the upper compartment. She shows the photo to Andi.

It is a photo of Bex on a hospital bed holding an infant baby. Bex then reveals the big secret: she is not Andi's sister. She is her mother.

Andi freaks out and calls in her parents, Celia and Ham. The parents confirm that Bex was telling the truth. However, Celia gets mad at Bex for telling Andi the truth when she wasn't ready. Andi gets frustrated that they have all been keeping secrets from her. She storms out and heads to Andi Shack - the shed where she goes for alone time, for creativity or to hangout with her friends. Bex follows Andi in the Andi Shack. She apologizes again for messing things up but asks Andi to understand. Andi admits that she is not really mad, but it will take time to get used to the new reality. She asks Bex who her father. Bex says that she is not ready for that yet but confirms that she has Andi's dad's photo in the memory box.

The following day, Cyrus and Buffy are ready to meet Andi before school. Cyrus has brought over Andi's motorbike but Andi admits that she is not ready for it yet. Buffy wonders why Andi never responded to her texts. Andi tells them that something really big happened on her birthday and she can't blurt it out. Cyrus mistakes it for Andi's first period and assures her that they totally understand and she doesn't have to spell it for them. The bell rings Andi leaves for her first period.

After school, Celia tries to confront Andi about her bike but Andi reminds her that they've lied to her her whole life. Celia assures Andi that nothing has changed. Sure, grandma!


Main Cast

Recurring Cast


Buffy: Hey! Watch where you're going, psycho!
Cyrus: You could have killed someone!
Andi: (takes off helmet)
Buffy & Cyrus: Andi!?

— Buffy, Cyrus, Andi

Andi: Yeah, something happened. Something really, really big.
Buffy: Are you gonna tell us?
Andi: I can't just blurt it out right here.
Buffy: Why not?
Cyrus: Buffy, are you not listening? She's a different person. Something really really big happened. (to Andi) We know what you're trying to tell us. You don't have to spell it out.
Andi: Trust me, you don't. (bell rings) I gotta go, it's my first period!
Cyrus: Exactly!
Andi & Buffy: What???

— Andi

Amber: Amber alert! Amber alert!

— Amber

Andi: I can't be here right now!

— Andi


  • This is the first episode of the season, and the series.
  • It was made available on WATCH Disney Channel, and VOD for free viewing on March 10, 2017.
  • Combined with "Outside the Box," this episode comprises the Andi Mack premiere movie, "Tomorrow Starts Today."
  • AM Lost Scene
    There was a deleted scene where Bex's absence at Andi's party terribly upsets the birthday girl.


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Andi Mack Episodes
Season 1
13Outside the BoxShhh!Dancing in the DarkIt's Not About YouShe Said, She SaidDad InfluenceTerms of EmbarrassmentShe's Turning Into YouHome Away From HomeWere We Ever?Best Surprise Ever
Season 2
Hey, Who Wants Pizza?Chinese New YearFriends Like TheseMamaThe SnorpionI Wanna Hold Your WristbandHead Over HeelsThere's a Mack in the ShackYou're the One That I WantA Good Hair DayMiniature GulfWe Were NeverCyrus' Bash-Mitzvah!Better to Have Wuvved and WostPerfect Day 2.0Truth or TruthA Walker to RememberCrime Scene: AndiShack!Andi's ChoiceFor the Last TimeBuffy in a BottleKeep a Lid on ItBought, Lost or StolenWe're on Cloud TenThe Cake That Takes the Cake
Season 3
The Boys are BackHowling at the Moon FestivalIt's a DilemmaHole in the WallThat Syncing FeelingCookie Monster