It's the hottest day of the year and Waffle is eating ice cream to cool down. Outside in the sweltering heat, Simon turns on the sprinkler to help everyone cool down, but poor Waffle doesn't like the sprinkler and darts through the hole in the fence to Mrs Hobbs's garden, looking for shade. The Brooklyn-Bells try to coax him back, but he refuses to return. Doug decides to make a mini swimming pool by filling the ball pit with cool water. Waffle loves swimming pools. Maybe that will encourage him back?

Waffle is unwell. He's in his pyjamas and under strict orders to stay in bed and rest. But poor Waffle can't get comfy. When he sees Evie and Simon playing in the garden, he feels left out and begins to woof and woof. Simon tells Waffle to rest quietly, but it's too late. The wonder dog's incessant barking has already disturbed Mrs Hobbs next door and, to make matters worse, like Waffle she's not feeling well either. Mrs Hobbs has a bad cold, and she's blaming it on the Brooklyn-Bells. She's convinced getting drenched in their ball-pit pond is the cause. The Brooklyn-Bells do chores for Mrs Hobbs to help her get better, and Jess brings home a surprise from work.

The Brooklyn-Bells are looking after the kitten from Jess's veterinary practice. When Waffle checks on the kitten, it's not in its bed. In fact, the kitten is nowhere to be seen. The Brooklyn-Bells don't see it disappear into the utility cupboard and through the tunnel to Mrs Hobbs's house next door. When Mrs Hobbs meets the kitten, she mistakes it for her beloved cat George. She falls in love with the kitten and doesn't want it to leave.

It's the day of Jess's 'bring a pet' birthday party. Gramps is one of the first to arrive with Muckypups and Thor, two pugs he's dogsitting for the day, and AJ and Anaya have also brought their pets, a gecko called Leo and three fish, Dipper, Dapper and Dopper. Simon and Waffle put on a show for their excited guests, performing the amazing tricks Waffle has mastered. Next to arrive is Mr Meagre and his talking parrot, Pickles. Pickles gives Waffle a run for his money when it comes to entertaining, and the two compete to be the star of the show. When everyone's attention turns to Pickles, Waffle, with the help of Simon and Doug, comes up with a plan to steal back the limelight.

Simon is taking Jess out for a birthday dinner, so Gramps is on babysitting duty. He's brought along Mr Willow's dogs, Trevor and Violet, for the evening. They look just like Waffle, and during a game of hide-and-sing the dogs all hide next door, causing confusion and chaos for poor Mrs Hobbs!

Waffle learns that the summer holidays will soon be over and Evie will be going to school. Determined not to be left alone, Waffle hatches a plan to keep the family at home.

Miss Berrington, Evie's new school teacher, and teaching assistant Mr O'Donnell have come to meet Evie at home before term starts, and Waffle is under strict instructions to be on his best behaviour. But Waffle is teething and won't stop chewing everything in sight.

While Zoe helps Doug with his homework project about Alaska, Simon and Jess take Waffle and Evie to the shops to buy new school shoes. But Waffle's attempts to help end up causing chaos.

Doug's tooth has fallen out, so Jess and Simon tell Waffle about the Tooth Fairy. Waffle longs to meet the Tooth Fairy and his dream comes true.

When Jess takes Evie for her first school visit, Waffle goes along too - on the condition that he doesn't sing. He tries his best to behave, but it's hard for a Wonder Dog! On their walk to school, Jess and Evie bump into Connie Lester and her daughter Ruby. Ruby reveals that she will also be starting at Sommersby School too, in the year above Evie. Ruby enjoys stroking Waffle and tells Evie that she loves animals. She has a pet dog of her own, Jelly, a yellow labrador. Waffle introduces himself to Jelly, but decides Jelly is a grumpy dog. Meanwhile, there's a For Sale sign in Mrs Hobbs's front garden. Mrs Hobbs and George are moving house and leaving Maple Close forever.

Connie and Ruby move into Maple Close with their dog, Jelly. Mrs Hobbs can't help but express her disapproval. She hates dogs and now there'll be another one living in close proximity. Waffle is not allowed to go on a family camping trip but accidentally goes on a different adventure!

Waffle is sad that Mrs Hobbs and her cat, George, are soon to leave Maple Close. The Brooklyn-Bells call on Mrs Hobbs to persuade her not to move house, only to find that her cat, George, has fleas. They offer to help and discover a secret about Mrs Hobbs.

It's Waffle's birthday and Mr Willow throws a huge party for him. As the Brooklyn-Bells prepare a surprise for Waffle, Connie and Ruby's dog, Jelly, leads the Wonder Dog astray.

Simon and Waffle are home alone. Simon recalls the first time he met Waffle as a pup, and the pair share memories of the Wonder Dog becoming part of the Brooklyn-Bell family.