Jack (Edward Furlong) didn't write his screenplay.
When his five day deadline is up, Penny (Kristin Booth) returns to collect Jack. When she isn't looking, he walks out of the freezer with *her* screenplay and locks her in. Grabbing the hand of her son Cole, he explains that he got a great idea during his five days; a crazy guy locks a woman in the freezer to write all the stories that he will publish under his name or he will hurt her son.
It is clear that is actually Jack's intention; to keep the talented Penny in a heightened state of fear that he will hurt Cole so she will continue writing scripts for which Jack will take all the money and credit for.
Jack ominously walks away with Cole, while Penny screams, pounding on the freezer door in vain.
Thanks Tim (Spectre)!