Saruman the white wizard of Isengard betrayed the Free Peoples of Middle-earth to the Dark Lord Sauron whose spirit had endured after the dark lord's defeat in Dagorland. Sauron gave Saruman orcs who took menial tasks of construction, excavation, blacksmithing, and working the furnaces. The Isengard crew discovered a special stone with magic during the excavation and Saruman decided to try it out.
The Fellowship of the Ring was established in Rivendell consisted of Frodo the young hobbit, Gandalf the grey wizard, Aragorn of the Dunedain, Boromir of Gondor, Gimli the dwarf of the Lonely Mountain, Legolas the elf prince of Mirkwood, along with the other three hobbits: Sam, Merry, and Pippin. They set out on the quest to Mt. Doom to destroy the One Ring to kill Sauron.
After the Crebain of Dunland reported to Saruman that the Fellowship was heading to the Redhorn Pass, the white wizard not only caused an avalanche on the Fellowship but also used the stone switching one of the Fellowship members with another individual from another world.
