"Glee" Star Dianna Agron Joins The Cast For "I Am Number Four" Dianna Agron, one of the stars of red-hot Fox series “Glee,” has nabbed the female romantic lead in “I Am Number Four,” DreamWorks’ adaptation of the upcoming young-adult science-fiction book by James Frey and Jobie Hughes. “Four” revolves around a group of nine aliens who escaped their home planet just before it was annihilated by a rival species. Hiding out on Earth, the title character, to be played by British actor Alex Pettyfer, disguises himself as a human high schooler, only to discover he’s still being hunted by his planet’s enemy. Agron will play a girl dating a high school jock who falls for Number Four and becomes his confidante. “Four” will be Agron’s big-studio debut. The role in the high-pedigree movie — Michael Bay is producing with Steven Spielberg, and D.J. Caruso is directing — was highly sought-after, and the studio went through several rounds of tests to find the right candidat