Sister Deborah is a healer and prophetess in an early 20th c. African-American charismatic cult that traveled to Rwanda to await the Second Coming. She could well be the “reincarnation“ of a famous queen and witch. We explore her life and others' through 2 POVs. The author based her novel on local history, mythology and stories, so that's another rabbit-hole to fall into. BTW, I loved the ending!
Pic of Lake Kivu: Adam Jones via Wikimedia Commons