Twenty-four people in masks. Twenty-five if you count the leader; 29 if you include the string quartet. Unknown location. Sounds mysterious. In fact, Hope & Refuge, a concert by the Elora Singers, will be available online for all to see and hear starting Nov. 14. The title is suited to both our troubled times and a program including Layton’s Letter to Canadians, a tribute to the late NDP leader by Jeff Enns, a member of the bass section. “It is optimistic and hopeful music,” says Mark Vuorinen, artistic director and conductor of the Ontario-based choir. “The piece is a setting of those wonderful words [Layton]…