It is, at times, much darker than you'd expect an animated children's Christmas movie to be. My son, 6 years old, was sometimes afraid while watching the movie, in spite of the humor, a strong plot, fun characters and excellent animation.

But, despite my son's misgivings, Klaus is poised to become the next big Christmas classic. It -- like Santa Claus is Comin' to Town, the 1970 stop-motion classic from Rankin/Bass -- tells the origin story of everyone's favorite holiday gift-giver.

In this case, the story centers around Jesper (voiced by Jason Schwartzman), a ne'er-do-well sent by his father to a feud-riven island in the far northern reaches to establish and operate a post office. (In this world, the postal service appears to be very important and powerful.) At first, Jesper fears for his life as the people of the wintry town of Smeerensburg -- led by aged combatants Mr. Ellingboe (Will Sasso) and Mrs. Krum (Joan Cusack) -- fight among themselves, but then he meets a reclusive woodcutter and toymaker, Klaus (J.K. Simmons), and hits on an idea to meet his 6,000 letter quota and free himself from his northern exile.

But, his plan to get the village children to write letters to Klaus asking for toys has many unintended side effects, among them the rejuvenation of the town's school, led by teacher Alva (Rashida Jones), because many of them don't know how to write. The goodwill the gift-giving sparks also has the benefit of making townsfolk genuinely nicer to each other -- some, very unwillingly, at first, but it grows to become second nature.

It all comes together magically, organically, and happenstance generates many of the legends we associate today with Santa Claus. It's beautifully drawn, laugh-out-loud funny and, at times, poignant enough to bring adults in the room to tears.

Klaus is a sweet family movie that I suspect will be shared among adults and children alike for years to come. By the end of our first viewing, my son and his twin sister were glued to the set. I expect their appreciation for this film will grow with them as they mature and learn to appreciate the full scope of the story.