The spirit of winter, Jackson Overland Frost - better known as Jack Frost is lifted with no previous memory from the depths of a frozen pond by the Man in the Moon, only to discover that no one can see or touch him. 300 years later, at the North Pole, Nicholas St. North, better known as Santa Claus , becomes aware that Pitch Black, the Bogeyman has returned and is threatening the children of the world. After alerting fellow Guardians the Tooth Fairy/Toothiana, the Easter Bunny/E. Aster Bunnymund , and the Sandman/Sanderson ManSnoozie to the problem, North learns that Jack has been selected by the Man in the Moon as the new recruit. Jack, frustrated and hurt by centuries of isolation, declines the invitation, but North persuades him to cooperate by explaining their mission and the looming threat.
Source from Wikipeida