Ian Hemlock is swept away to a magical land after he falls out of an attic window and embarks on a quest to find a slipper for a dead girl who can help him find his missing father.

Sorry I left out the "magical world." Which is important to the story. after he falls out of an attic window, a young boy lands in a magical world and embarks on a quest to find his missing father?

I think the the slipper does not need to be mentioned here becuase it is not the main conflict. The conflict is finding his father. Anything that leads to that should not be in the logline. "after he falls out of an attic window, a young boy embarks on a quest to find his missing father" Boom, short and sweet :)

A young boy who falls out of an attic window, is swept away to a magical land where he embarks on a quest to find a slipper for a dead girl who can help him find his missing father.

Thanks you.