Tim Kasher has always been at his most impressive when telling stories. Thanks to Kasher’s honesty and artistry with words, his band Cursive has repeatedly turned good indie-rock songs into life-or-death explorations of tumult and love — aka great indie-rock songs. With “I Am Gemini,” the Omaha, Neb., outfit’s seventh record, the frontman assembles a multi-act, multi-character play about twin brothers Cassius and Pollock, based on the mythological, egg-hatched Castor and Pollux. It’s a painstakingly constructed project rich with chimerical phrasing and ample opportunities for Kasher to sort out his issues — precisely the kind of platform he needs to demonstrate his talent. Cursive performs at the National with Minus the Bear and Caspian on Sunday, Sept. 30, at 8 p.m. $20-$23. thenationalva.com.