Texas indie band Okkervil River released its sixth full-length, “I Am Very Far,” in May and the album’s already getting numerous accolades from critics. After a run of concept albums, front man Will Sheff and his bandmates return with a collection of unrelated songs that are dark and mysterious. It’s a big departure from how the group has operated so far, but fans love it. Expect to hear many of those new tracks, plus plenty of the group’s other more conceptualized hits, when Okkervil River performs at the National on Sunday, Sept. 11, at 8 p.m. $18-$21. 612-1900.