In this issue: COMMENT "Dangerous Gamesmanship", by Steve Coll: Republicans could be further fragmenting American power by meddling with President Obama's negotiations in Cuba and Iran. A REPORTER AT LARGE "Where Are the Children?", by Sarah Stillman: For extortionists, undocumented migrants have become big business. ANNALS OF TECHNOLOGY "The Man Who Broke the Music Business", by Stephen Witt: The dawn of online piracy. THE ART WORLD "New York Odyssey", by Peter Schjeldahl: Renzo Piano's new museum is an instant landmark on the cultural, social, and poetic maps of the city.