You probably first heard the Watson Twins on Jenny Lewis' Rabbit Fur Coat. Chandra and Leigh Watson sang backup and received co-billing on the Rilo Kiley frontwoman's debut solo album two years ago, instantly netting indie cred. On their second album, Fire Songs, the Watsons aim for a more mainstream audience with sweet songs sung in perfect harmony. It's so mellow and relaxed, Natalie Merchant sounds like a wild tiger in comparison. Even the girls' cover of the Cure's peppy "Just Like Heaven" appears ready for naptime. Only the '60s-style pop of "How Am I to Be" picks up the pace. Fire Songs is like a swimming pool with too much chlorine: It's all cool and refreshing at first, but after a few minutes, it begins to painfully assault your senses.