Harry Angel, a down-and-out Brooklyn detective, is hired to track down a singer on an odyssey that will take him through the desperate streets of Harlem, the smoke-filled jazz clubs of New Orleans, and the swamps of Louisiana and its seedy underworld of voodoo.

When a stolen white stallion escapes his captors, young Stephanie Ward gives him a new home and a new name: Lightning. As she grooms the horse for show-jumping competition, the pair forms an unbreakable bond. But when Stephanie finds herself in need of an expensive operation, and Lightning's original owner tracks him down, Stephanie sets all her hopes on first prize at the Nationals - and on the horse who's become her best friend!