As she beheld her, poor Mrs. Mack's heart fluttered up to her mouth, and then dropped with a dreadful plump, into the pit of her stomach.

I have fixed the parts I understand, and the rest leaves me at a loss.

An episode of The X-Files […] further dramatizes the insidious potential of computer-controlled nanosites loosed in a human body. FBI Assistant Director Skinner (Mitch Pileggi) lies rigid on a hospital bed.

The first night was a disaster, and the cast were mostly in tears.