Last week, Payton Leutner, the victim in the Wisconsin “Slender Man” attack in which two of her schoolmates stabbed her multiple times as tribute to a fictional ghoul (one they believed to be real), spoke out for the first time since the horrific event. That’s serendipitous timing for Underscore Theatre Company’s new musical by composer Alexander Sage Oyen and book writer Austin Rega. In Proxy, Vanessa (Carisa Gonzalez) is 15 years out from the time her best friend, Veronica, or Ronnie (Tessa Dettman), plunged a knife into her torso a dozen times.

It’s a tribute to Gonzalez and Dettman in particular that they make the scenes between the two women carry so much emotional weight, divvied up by measures of regret, confusion, rage, and a numb but palpable sense of compassion. There’s the nugget of a great question here: How do we forgive the worst thing that ever happened to us, and do we need to do that in order to fully live again?

Through 11/24: Fri-Sat 7:30 PM, Sun 4 PM, Mon 7:30 PM, the Understudy, 4609 N. Clark, underscoretheatre.org, $25.