Sisters Bianca and Sierra Casady — aka CocoRosie — mesh folky guitar, piano and harp with electronic instruments, and even tease music out of children’s toys. Their basic premise of “freak folk” has been in place since the 2004 debut La maison de mon rêve, but despite its strangeness, CocoRosie’s music remains engaging and catchy. Though their aesthetic leans towards surreal, their subject material is the stuff of nursery rhymes and spirituals, reinterpreted through the lens of the spooky harmony between the two near-identical sopranos. The effect sways between sad, gorgeous and ambiguously nightmarish, and sometimes manages to be all three at once.

Sun., Sept. 7, 8 p.m., 2014