After a one-year hiatus, Outside the Box returns with a second helping of music, dance, theater and more. This performing arts festival that debuted in 2013 offers a free showcase for hundreds of local, national and international artists on Boston Common July 14–19, to the delight of the thousands of spectators who are expected to attend. A Southern twang has been added this year with the inclusion of a country music night on July 17, headlined by country star Kacey Musgraves (pictured). Another new feature is the incorporation of Radio 92.9’s EarthFest into the larger festival, as that event moves from the DCR Hatch Shell to the Common this year. The July 18 show is headlined by locally bred alt-rockers Guster, who are joined by New Politics, Atlas Genius and “American Idol”’s Alex Preston.