The episode starts with Bandit driving the SUV. Chilli is sitting in the front passenger seat, and Bluey, Bingo, and Muffin are sitting in the backseats.
Muffin: What can we pway at your house, Bluey?
Bluey: I'm not sure.
The SUV drives up and past Doreen's house, Bandit looks out the window.
Bandit: Oh, look. Doreen's having a garage sale.
Doreen waves at the Heelers. Bluey, Bingo, and Muffin are looking back at her.
Bluey, Bingo and Muffin: Oooh! (The cousins then spot something) Ah!
Bluey, Bingo, and Muffin spot a scooter with a sign for $300; excited, they shout...
ALL: GRANNY MOBILE!
TITILE CARD - GRANNY MOBILE. A plate being held up is shown.
Muffin: (reading) This episode of Bluey is called 'Granny Mobile'.
A wide shot of Doreen's garage sale is shown, showing a wide variety of items. Chilli and Bandit arrive at Doreen's garage sale to have a look.
Chilli: Having a bit of a garage sale, Doreen?
Doreen: Yes, love. I'm trying to get a bit of cash to go on holiday to the reef!
Bandit: (Pointing to the scooter) Well, if someone buys Len's old scooter, that'll help.
Doreen: Oh, yeah.
A shopper walks over to Doreen, holding a painting.
Shopper: How much is this?
Doreen: Oh, whatever you think, love.
The scene cuts to show Bluey, Bingo, and Muffin starting their game of Grannies.
Bluey: Okay. Let's decide what sort of grannies we'll be.
Bingo: (Pulls the shawl over her head) I'm going to be a can't hear anything granny.
Bluey: I'm gonna be a kind granny.
Muffin: What sort of granny can I be?
Bluey: Oh. Um. I'm not sure there are any other types of grannies.
Muffin's expression quickly sours and she throws a small tantrum.
Muffin: Ugh, it's not FAIR! I KNEW I wouldn't get to be a granny!
Bluey: Ah, that's it! You can be a grouchy granny!
Muffin quickly becomes happy again.
Muffin: Oh yeah.
Muffin grumbles and makes an angry face, leading Bluey and Bingo to giggle.
Bluey: And make it that you want to sell us your granny mobile.
Muffin: Okay.
Bluey: Let's go, Bingo.
Bingo: Pardon?
The scene cuts back to Doreen with the same customer who was asking the price for the painting. But this time, he is holding a vase.
Shopper: How much do you want for this?
Doreen: Oh, well, what do you think?
Shopper: Two dollars?
Doreen: Okay. That's fine.
The shopper hands her two dollars and walks off. In the background, Chilli overhears their conversation and is sadden by the fact that Doreen could have sold it for more than that amount.
Doreen: Thanks.
Chillie walks over to Doreen.
Chilli: Doreen! That vase is worth way more than that.
Doreen: Oh, I don't want to make a fuss.
The trio of grannies (Bluey, Bingo, and Muffin) then walk up to Doreen.
Bluey: Doreen, can we play with your granny mobile please?
Doreen: Go for it. I'm taking the battery out, so it won't move.
Muffin: Oh yes it will! (Pokes Bandit's leg). 'Bugalugs' is going to push it!
Bluey and Bingo: Yeah!
Bandit: Am I 'Bugalugs'?
Soon, Muffin, now the grouchy granny "Gladys", is being pushed along the scooter by Bandit Bugalugs.
Muffin: Faster!
Bandit: Yes, nana.
Muffin: (Pointing the ground) And you're going over too many cracks.
Bandit: It's a footpath!
Muffin: (hits him with her bag) Don't talk back to me, sonny!
Bandit: Gee, you are one grouchy granny.
Bluey and Bingo are standing in front of the house. Muffin gets pushed over.
Muffin: Stop. I said STOP!
Bluey and Bingo laugh.
Bandit: Okay, nana.
Bluey: Hello, Gladys.
Bingo waves at Muffin.
Muffin: Ugh. I'm selling the granny mobile. Are you gonna buy it?!
Bluey: Oh. Well...
Muffin: Make up your mind!
The duo gets started by Muffin's unexpected shouting, before laughing again.
Bandit: Nana!
Bluey: How much is it, love?
Muffin: Bugalugs, what number is this?
Bandit: Uh, $300 dollarbucks. (To himself) Oh, Doreen, you can get more than that... (To Muffin) Let's say $900!
Muffin: $900 dollarbucks.
Bluey: How much money ya got, Rita?
Bingo: Pardon?
Muffin: HURRY UP! My hips hurt!
Bingo: Let me count ma' coins. (does so but slowly) One... two... oh, that's a nice-
As she's counting, Muffin starts to get increasingly annoyed, then she becomes agitated as she twitches her eye. Finally, she completely loses patience and screams:
Muffin: HURRY UP!
Bingo drops her purse, spilling coins everywhere. Bluey gives a small laugh.
Bingo: Oh, my coins...
Muffin: This is taking too long! Bugalugs, take me home!
Bandit: Yes, nana.
Muffin: And watch the CRACKS! (Points to the ground again)
Bluey and Bingo laugh again.
Bandit: Sorry, nana.
Muffin stops the play for a beat.
Muffin: Bluey, grouchy granny is a bit too gwouchy. Are you sure there isn't another type of granny?
Bluey: There might be, but I just don't know what it is. Do you?
Muffin: (Thinks about it for a second) Hmm... no. I'll stay grouchy granny...
Bandit: Oh, great.
Muffin: (now the grouchy granny and hitting him with the bag again) You watch yourself, young man!
The scene then cuts back to Chilli, the shopper, and Doreen back at the garage sale. With the customer wanting to buy a statue.
While Doreen is speaking, Chilli motions her arms to signal her to bring the price up.
Doreen: Hmm... how about five dollars?
Chilli immediately becomes annoyed.
Shopper: (Unamused) How about two dollars?
Doreen: Okay, two dollars.
Doreen gets handed $2 once again. Chilli sighs.
Chilli: Doreen... If you wanna go on a holiday to the reef, you better toughen up.
Doreen: Oh, I know...
An old pug walks up, and bumps into a table. Knocking over and breaking a cup and saucer. She shouts after doing so.
Doreen: Oh, dear.
Old Pug: The table leg's blocking the footpath. I could've break my leg!
Doreen: Oh, I'm terribly sorry.
Old Pug: I should call the council!
Chilli: I'll get it, Doreen.
Chilli pulls the table back a little.
Old Pug: Keep that noise down!
Chilli: I'm sorry?
Old Pug: I'm not paying for any of this!
Chilli starts cleaning up the debris.
Doreen: Oh, well. That's fine.
Chilli: Well, I think you should pay a little.
The Old Pug starts walking away.
Old Pug: I think you should mind your own business!
Chilli: Woah. That is one grouchy granny.
Muffin gets wheeled back.
Bandit: We're back home, nana.
Muffin: About time! Now, make me a cup of tea, Bugalugs!
The Old Pug walks over to the scooter.
Old Pug: (To Muffin) Hey, you, get off there!
Muffin: No! It's mine!
Old Pug: I'm buying it.
Muffin: Fine. Give me $900 dollars.
Old Pug: What?! The sign says $300.
Muffin quickly grabs the sign and throws it away to make her point clear.
Muffin: EH! $900 DOLLARS!
Old Pug: I'm not payin' 900 dollars!
Muffin: Good. Then I keep it! (Crosses her arms and looks away from the old pug)
Old Pug: Oh, it's like that, isn't it?
Bandit goes over to where the old pug is and tries to calm her down. But the battle of the grouchy grannies had just begun!
Bandit: Oh, look, love, I think you want to talk to that lady...
The old pug hits Bandit with her purse.
Old Pug: Get your hands off me!
Bandit: Ow! What are you doing?
Muffin hits him as well.
Muffin: Where's my cup of tea?!
Bandit: Doreen, I think this delightful lady wants to buy your scooter.
Old Pug: $100 dollars.
Doreen: Um, I guess that sounds okay.
Bandit: Oh, Doreen, you need to go higher than that.
Old Pug: (To Bandit) You need to lay off the biscuits!
Bandit: What?! (to Chilli) You said I was looking good!
Chilli: You are honey. Ignore her.
Old Pug: Oh, nosy neighbor's back.
Chilli: Now, you listen!
Old Pug: $100 dollars. Take it or leave it.
After a few seconds, Doreen unfortunately gives in and takes the $100...
Chilli: Oh, Doreen, no...
Old Pug: (To Muffin) Right. You, off.
Muffin: No!
Old Pug: What?!
Muffin: I told you; it's $900 DOLLARS!
Bandit is now by a mirror, examining his body fat.
Bandit: A lot of this is just water weight.
Chilli: Muffin, honey, why don't we-
Muffin: Hands off!
Old Pug: Stay out of it, Cattle Dog. $200, final offer.
Muffin: Ten hundred!
Old Pug: What? You're dreamin'! (pulls out more money) 500.
Muffin: Eleven!
Old Pug: Outrageous!
Muffin: If you don't want it, then don't buy it!
Old Pug: I'm not paying eleven hundred dollars!
Muffin: Why not!?
Old Pug: 'Cause it's ugly. Like her hat.
The old pug points to Doreen's hat.
Chilli: Hey, hey!-
Chilli starts to advance towards the old pug, but Doreen stops her.
Doreen: Hang on, love. Let's see how this plays out.
Old Pug: And another thing, I don't like the colour.
Muffin: Well, PAINT IT!
Old Pug: You paint it.
Muffin: You paint it!
Their argument between painting the scooter goes on in the background as Bandit gives his side a tap.
Bandit: Oh yeah, it jiggles.
It cuts back to Muffin and the old pug.
Muffin: No, YOU paint it!
Old Pug: Fine. (pulls out more money) Eleven hundred.
Muffin: TWELVE HUNDWED!
ALL (but Muffin): What?!
Muffin: And 18 lollies!
Old Pug: Oh, you cheeky little... fine. $1200 dollars.
The Old Pug pulls out the money, to which Muffin looks at her with a smug expression, obviously proud that she managed to bargain a really good deal!
Doreen: Oh, my goodness!
Old Pug: And how much are the lollies?
Chilli: Oh, $2 dollars!
Old Pug: Oh!
The scene briefly shows an item on the table: A royal wedding commemorative plate of Princess Diana and Prince Charles. After a few seconds, the scene cuts to the old pug driving away in her new scooter.
All: Bye!
The old pug blows a raspberry at them.
All: Hooray!
Chilli: You'll be going on that holiday now, Doreen!
Doreen: Yeah.
Bandit: I'm gonna do some push-ups.
Bandit walks off, Muffin has a jar of lollies in her hand and eats a few.
Muffin: Hm. These lollies are gross!
Doreen: Muffin, look around. You can pick anything you want.
Muffin: Really? (tail starts wagging)
Doreen: Yep. You are one in a million. (Places her hand on Muffin)
Muffin giggles, and spots something she wants. She grabs it, revealing a red tea towel.
Muffin: Can I have this?
Doreen: Are you sure? Just a tea towel?
Muffin slightly nods in response.
The scene then cuts back to Bluey and Bingo. Bingo drops her coins on accident.
Bingo: Aw, ma' coins.
Muffin runs in, singing.
Bluey: Oh, look, Rita. It's the Super Granny!
Muffin: May I help you with those coins?
Bingo: Pardon?
The scene finally cuts back to Doreen's yard, Bandit is doing sit ups while Chilli is folding some of the tables.
Doreen: Bandit, I've got one of those exercise thingies if you want.
Bandit: Oh yeah. How much you want for it?
Doreen: Oh, I don't know. What do you think?
Bandit: 20 bucks?
Doreen: Hmm... (She places hands on her hips and then talks with confidence) 50!
Bandit: Ha! Doreen!
Chilli: That's my girl.
Episode ends. The old pug drives past the credits.