Summer, 1967. Two Massachusetts boys – 9 and 11 – set off on an improbable journey with their family pet, a Shetland pony named King. Tony and Jeff Whittemore are desperate to visit Expo ’67 in Montreal – the largest World’s Fair ever. But their parents can’t take them. Then Mom comes up with the solution: hitch their pet Shetland pony King to a cart and drive 350 miles to Expo 67 – on their own – at 5 m.p.h.! For Tony and Jeff, it becomes the adventure of a lifetime.