Like some movie assassin, Dave Grohl is a man leading a double life. On the one hand, he’s the mild mannered musician and contented family man who disarms all who meet him. On the other, he’s the Foo Fighters‘ songwriter, who goes to work doing something much more aggressive: the heavy, cathartic business of casting his demons out. This sees him doing that (not least in the excellent opener “The Pretender”), but it also attempts to reconcile more of his contrary impulses. On the last Foos album, “In Your Honour” rock and acoustic music were exiled to different discs. Here, a satisfactory compromise is brokered between the two: the excellent “Summer’s End” is easy on the ear, easier still on the brain, and sets him up in the radio-friendly “Wonderwall” district one imagines is his spiritual home.