Born in East London to Jamaican parents, Elaine Mitchener deploys a three-octave voice trained in opera—glistering crown of Western civilization—to explore its blistered underbelly. Her appearance in Dartington’s Great Hall, a 14th-century pile refurbished with Whitney cash, is part of a three-day symposium (October 29 to 31) in which “decolonial” thinkers explore issues of race, empire, and environmental harm. If that sounds too painful, consider that also on the bill is the London free-jazz trio Shifa, whose name is Arabic for “healing.” —E.E.