Transcript for '20/20' Exclusive: 'Slender Man' Attack Survivor's Story
Friday David Muir reporting a survival story so unbelievable and so shockingly real. A twelve year old and what started out as a -- she's gonna go roller skating it's been an editor best friend's house can't. Took a horrifying turn you think she had any idea. What she was walking into -- now. -- -- -- -- TV -- with one Finley and their harrowing story why would 212 year old girls try to -- brutally stabbed their friends. Nineteen times he told police wanted to kill the victims so people would eldest -- -- real. Over a mysterious fictional figure on the Internet how do you even -- their heads about it's just too. For the first time anywhere firsthand moment by moment chilling details from the family from -- left alone to die in the with the security there -- multiple -- -- how she miraculously fought off -- where on earth do you think she -- the strength to crawl out of us what's she. So I wanted to live -- -- -- hugged her and -- -- -- going to be OK it's going to be but I could see that she was covered in stab wounds. It -- it takes is one -- mind. David -- and for the first time. Meet at twelve. She's an amazing time. She's definitely are -- and prepare. One -- message to parents around. -- the stunning 21 twins' season premieres Friday at 10:9 central on ABC.
This transcript has been automatically generated and may not be 100% accurate.