The inhabitants of Wheelie World have all been asleep for years thanks to a spell by the evil witch Fenella. But suddenly an egg appears in Wheelie World and when it hatches a happiness dragon emerges that will break the evil spell.
The Wheelies are in trouble, their wheels and tires are wearing out and they have no replacements as Fenella the witch has cursed the plants in the spare parts orchard. Can Chorlton lift the curse and save his wheeled friends?
Seeing that Chorlton has gone picking flowers, Fenella plants a trail of beautiful flowers to lure the dragon to Spout Hall. She plans to capture him there. The Wheelies organize a search party but they needn't worry about him.
Fenella summons an Octoblob to lure Zoomer to a disguised Spout Hall. She plans to take the speedy Wheelie prisoner so that she can exchange him for Chorlton. But does the witch really want a happiness dragon in her home?
Fenella seems to have come up with a foolproof plan to get rid of Chorlton once and for all - frame him for a crime. So she steals King Otto's crown and magically leaves a trail of dragon-sized footprints - but she makes a mistake.
Everyone in Wheelie World is spring cleaning - except Chorlton. The happiness dragon has no wheels, so has no springs to clean. The Wheelies give him a Wheelie Cart to travel around on - much to the annoyance of Fenella the witch.
The hot weather is making Fenella cross, Riley the telescope droop and the Wheelies vital sarsaparilla stream dry up. Chorlton and the Wheelies go off to drill for sarsaparilla. Has Fenella got a spell to stop them drilling?
All of the Wheelies are getting ready to play their favorite sport - Wheelie Hockey. They invite Chorlton the happiness dragon to join in, but he finds it all a bit confusing. Fenella the witch tries to sabotage their fun though.
Chorlton is puzzled when all of his Wheelie friends are being very secretive. It is one year since the happiness dragon appeared and they are planning a surprise birthday party for him. But Fenella is planning her own surprise.
When the Wheelies hold a dance festival Chorlton feels left out. Fenella tries to spoil the fun with some magic dance pumps that will freeze anyone who dances with her. But Chorlton finds a duck that can teach him to dance.
The Wheelies plan to stage their annual great race in honor of Chorlton. But Fenella the witch uses her magic to create a racing cart so that she can enter and win the race. She tries every dirty trick there is to try and win.
Chorlton disturbs the peace of a Bank Holiday when he finds a strange object. It is a musical instrument and soon his playing encourages the Wheelies to reform their brass band - much to the annoyance of Fenella the witch.
It is Christmas time in Wheelie World. Zoomer goes off to get a Christmas tree for the square but finds that Fenella's miserable magic has withered them all. It is up to Chorlton to spread some festive cheer even to Fenella.