To prepare readers for the difficulty of the days that lay ahead.
The sentence that uses the word them as an indirect object would be Leo sent them a postcard from NASA.
Hope this helps and good luck with whatever it is you're doing!
A MacGuffin is that object in a film which is critical to the characters, but carries insignificant meaning for the audience.
A MacGuffin, a term introduced and widely used by Alfred Hitchcock is some element which drives the plot. The audience is not very concerned with the specifics of it.
