The Northborough Free Library will be hosting two local mystery authors at a special event Wednesday evening. They will share their writing experiences, answer questions from the audience, and sign copies of their novels. Steve Ulfelder lives in Southborough and wrote his first novel, “Purgatory Chasm,’’ last year, receiving notable praise and winning the RT Book Reviews’ Best First Mystery. The book was also nominated for an Edgar Award. His second novel, “The Whole Lie,” was published this year. Also visiting the library will be Belfast native Kyle Darcy, who lives in the Boston suburbs and used the city as inspiration for his first mystery novel, “Under Current Conditions.” The free event, part of a summer reading program for adults, will begin at 7 p.m. in the library’s meeting room.