Long before he learned to dunk on warped wooden backboards, Awet Eyob nursed a dream: to play basketball in America. He is 6-foot-8, built like an oak tree, and seems to have mastered a behind-the-back dribble and crisp passes from the corner of his eye. But one big problem stood between him and his dream: his homeland, Eritrea, an isolated, secretive nation in the Horn of Africa that is refusing to let its young people leave.