It's Halloween, and Blaze and his friends are having fun truck-or-treating and getting candy. But when Crusher's attempt to steal the candy sends it far away, the Monster Machines have to find it before Crusher can get it first.
On Halloween night in Axle City, cars are enjoying themselves when Blaze and AJ appear. Both introduce themselves to the viewer and show off their costumes: Blaze is a knight, and AJ is a superhero. They then show their buckets of candy and invite the viewer to go truck-or-treating with them.
After truck-or-treating at the Axle City garage and getting candy from Gabby, Blaze's friends show up, also wearing costumes - Starla a witch, Zeg a king, Stripes a pirate, and Darington an octopus - and holding full buckets of candy. When Darington hops in front of a light, he sees something on the wall mistaking it for someone in a costume when really it's his shadow. Blaze then projects a light onto a building to demonstrate; when AJ gets in front of the light, he makes a shadow of his own, and he even changes his position to make his shadow look like a bat.
As the Monster Machines have fun making shadows, none of them notice Crusher coming up the block, along with Pickle dressed as a banana. When Crusher wonders what's so special about Halloween, Pickle gives him all the information. When he mentions getting candy, Crusher suddenly perks up, and upon seeing Blaze and his friends' candy unattended, he gets excited and wishes he has it. Pickle thinks he's going to truck-or-treat, but Crusher decides to steal it.
Constructing a Halloween Candy Stealer, Crusher steals the buckets one by one while the Monster Machines are not looking. But the machine doesn't stop and explodes, sending the candy flying away. Blaze and the gang notice, and spot Crusher heading after it. Blaze declares they have to get their candy back before Crusher does. The group heads off, Blaze singing Hit The Road in the background as they start their journey.
Upon reaching a foggy forest, AJ uses his Visor View to locate the candy near a faraway barn, but not even a few moments later, the fog is so severe that Blaze's friends cannot see where they're going and get stuck in the mud. When Blaze hears them, he cannot see them, but he decides to find them using shadows cast by the light of the full moon. He succeeds at finding them with help from the viewer. They set off again, testing out their shadows as Blaze and AJ sing a song about shadows in the background.
Meanwhile, Pickle tells Crusher his favorite part about Halloween is wearing a costume, and slips away while Crusher is brooding about candy mid-sentence. He then sees a shadow on the wall, thinking it's a monster and hides, but it's really Pickle dressed as a butterfly. Crusher then spots Blaze and the gang coming right up the path and blocks their way with rocks so they don't follow him. Luckily, AJ spots a shortcut through a nearby tunnel.
Not even a few seconds into the tunnel, Starla and Zeg begin to laugh uncontrollably. Blaze discovers they're being attacked by tickling spiders, which attach to them and tickle them nonstop. The whole cave is full of spiders, so they have to get out fast. Along the way, the spiders begin to make webs to stop them from leaving. For each one, Blaze warns the viewer they have limited time to get past the web before it closes; they succeed with the viewer's help and continue on.
Not very far, Crusher is singing to himself about candy when he sees another shadow on the wall of a shed, thinking it's another monster when it's really Pickle dressed as a shoe. He then sees Blaze and the gang charging forward and makes a Robo-Pumpkin launcher to stop them.
To get past the robo-pumpkins, Blaze needs something to chop them: a reciprocating saw. He transforms into one and heads after the launcher, and with help from the viewer, he slices one after the other and destroys the machine. The trucks congratulate him and they finally spot the candy, but Crusher is about to grab it.
Blaze then remembers they can scare Crusher away with a shadow. Casting his light onto the barn, AJ makes the bat shadow with his costume from earlier, and as Crusher is about to get the candy, he spots AJ's shadow and is scared, thinking it's a bat and hurries away in a panic as Pickle follows. The gang congratulates him and get their candy back, and enjoy it as they celebrate and wish the viewer a Happy Halloween.
Back in Axle City, Crusher is upset he never got any candy, but Pickle reminds him there's still time to truck-or-treat. Crusher then spots a present box off to the side and decides to get candy from that, but Pickle isn't sure; when Crusher opens the box, all he finds is a tickling spider, and it clings to him as he hurries off into the distance.