Echo Hall Murders

After the mystery writer Wen Shaoting passed away, six related people were invited by his will to come to the "Echo Hall", the old house in Wudeng Mountain, to witness the unsealing of the posthumous manuscript "The Key to Silence". Everyone thought it was just a publication review, but on the first page they read an old case that had been buried for twenty years. When the key figure Xu Jiming entered the study alone, he died in a secret room that was bolted from the inside. The tea was non-toxic, the doors and windows were closed, and the murder weapon was unknown. The only thing unusual was the thirteenth page he was holding tightly in his hand...