Watch Online Free HD Solarmovies. When Scooby and Mystery Inc. visit an off-road racing competition, it's not long before strange events start to occur. A mysterious phantom racer, known only as Inferno, is causing chaos and is determined to sabotage the race. It's up to Scooby-Doo, Shaggy and their new driving partner, The Undertaker, to save the race and solve the mystery.