A Meteorite crashes into a remote part of earth, boring through until it reaches the centre.
Tremors are felt miles away, until a humanoid baby Breaks its way through the ground to the surface.

(Not revealed yet, but the baby was sent in the meteorite to destroy infant inhabitants of another planet, unbeknown to the baby, the meteorite went off course)

The baby is found wandering by a childless couple who take pity and decide to take it in.
whilst living with the couple the baby continues to wander and See's his surrogate father chopping down trees with a chainsaw.
Needless to say the parents are butchered, and the rest of the film shows the town police trying to find a killer, unbeknown that it's the baby the whole time.

i haven't come up with an ending, as it will be made into a trailer, and it's not as though we'll be showing it.

any thoughts let me know :)

EDIT: Plot holes filled:

The baby's humanoid figure is ignored by the adopting parents as they have wanted a child of their own for so long

The chainsaw is a small crankshaft chainsaw, able to be wielded and operated by a small child