Mike: Chubbuck, can you get out there?
Christine: Uh, no, sorry. I can't.
Mike: What do you mean, you can't?
Christine: I'm tucking in that hospital piece. I need more time.
Mike: You're shitting me. I thought you finished with that last week.
Christine: That was Part One.
This is a scene from the Movie Christine. From the context "tuck in" apparently means to wrap up, to finish off. Christine is saying she needs to wrap up her other commitment. It seems to me this sense comes from "tuck in" meaning to put someone to bed, but I haven't heard the phrase used figuratively like this. I wonder if this is the scriptwriter's creativity speaking or is the phrase idiomatic and commonly used?