Chloe Grace Moretz listens to the desperate 911 call made after the Columbine high school massacre every night before she steps on stage to perform in chilling new play The Library.

Moretz made her New York stage debut last month (Mar14) when she kicked off her run in the production, directed by Hollywood heavyweight Steven Soderbergh, which focuses on a survivor of a fictional high school shooting incident.

To understand the frenzy of the situation, she closes herself off and listens to a call made to police after the notorious 1999 killing spree at a school in Columbine, Colorado before the curtain comes up.

She tells America's Interview magazine, "I sit down and put my headphones in, listen to on a couple of songs, and think about a couple of people - to start to wrap my head around the whole thing and the darkness of it. Then, two minutes before I walk on stage, I watch real video footage - the 911 call - from Columbine. The video finishes right before I step on stage to go lie on the table for 15 minutes before we open the house and start the show."

The Columbine massacre was carried out by two students, Eric Harris and Dylan Klebold, who gunned down 12 youngsters and a teacher, and injured a further 24 before committing suicide.