Friend's first collection suggests that the "New Yorker" staff writer would make a killer cocktail-party guest: His essays and articles range from the sobering (a moving postmortem on River Phoenix's death) to the sublime (America's early-90's acceptance of white-trash culture). And while "Lost" focuses primarily on popular culture (a subject Friend approaches with a mix of fanboy enthusiasm and grown-up skepticism), it takes unexpected detours through the Philippines, Morocco, and, of course, Mongolia itself--where a routine travel story suddenly becomes a moving tribute to a curmudgeonly travel companion. A-.