Frankenstein was born with a heart disease, which made any kind of physical effort a serious risk to her life. But her feeble body harbored tremendous magical power—a threat of entirely different sort, lurking within her like a monster. Mary feared that power and always kept a close watch over her sister.

Frankenstein was born with a heart disease, which made any kind of physical effort a serious risk to her life. But her feeble body harbored tremendous magical power—a threat of entirely different sort, lurking within her like a monster. Mary feared that power and always kept a close watch over her sister.