The Riddle of the Door

The bronze eagle doorknocker invents a riddle so difficult/strange/obscure that no-one can get into Ravenclaw Tower. Headmaster Snape grudgingly agrees to bring in an expert from the Department of Mysteries. Severus has the school's secrets and students to protect, and Hermione has a riddle to crack. HP fanfic written for the 2018 SSHG Gift Fest. As always, JKR owns everything.