A Heart of Darkness is the eighth episode of the third season of Shadowhunters: The Mortal Instruments.


Magnus, Alec and Isabelle try to reach Jace inside The Owl, but even as powerful as Magnus is, can he help the Lightwoods retrieve their brother from his demon prison? Maia and Jordan join Simon on the hunt for Lilith, while Luke tries to find a way to get to Clary.



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The following are elements adapted from The Mortal Instruments book series:

  • The woman Robert was having an affair with was Annamarie Highsmith.
  • Simon had the Mark of Cain on his forehead protecting him and wreaking havoc on others, and was also a threat to Lilith.
  • Maryse used to sing her children, including the adopted Jace, the French ballad À la claire fontaine before bed.
For differences, see here.


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