Dennis recruits Grizzly Griller to help make school sports day more extreme, but as he and JJ get competitive against each other, who is sabotaging both their chances of winning?

Dennis needs to pull off a magnificent stunt to save the skate park from closure, so Gran gives him the skateboard of the legendary Kendo 360 to help. When the special board goes missing at the worst possible moment, Dennis needs to dig deep and realize that it's the skater, not the board that's important.