Speed wants to turn professional, but Pops objects to his plans. Meanwhile, Pops plans to build a powerful new engine for the Mach 5 on his own after his employer rejects the design. But the executive is actually plotting to steal the design.

Continuing the race, Ace and his gang goes after Pops' designs. How will Speed Racer protect the designs from being stolen by the gang?

Speed is determined to enter his first big race against Pops' wishes. His drive to prove himself culminates in a challenge race on a stormy night against the Masked Racer (Racer X).