'Fanatical: The Catfishing of Tegan and Sara' review: A true crime doc about toxic fandom

Catfishing is perhaps the only place the work of Tegan and Sara and Erin Lee Carr could collide. After all, the former are a Canadian indie pop duo and the latter is a true crime documentarian. While the titular twin singer/songwriters deliver beautiful and achingly catchy songs about break-ups and sapphic yearning, the latter filmmaker has explored the dark depths of shocking cases like the Bling Ring thieving spree, the despised "cannibal cop," the murder of the notorious DeeDee Blanchard. 

In Fanatical...