Heat Vision is reporting that Glee's Dianna Agron has signed on for the female romantic lead in the D.J. Caruso-directed I Am Number Four, DreamWorks' adaptation of the upcoming young-adult science-fiction book by James Frey and Jobie Hughes.

I Am Number 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.

Sharlto Copley is already on board as Four's mentor, while Teresa Palmer is cast as Pettyfer's fellow alien, Number Six.

Alfred Gough and Miles Millar wrote the screenplay.

I Am Number Four is scheduled to begin principal photography next month in Pittsburgh.