Little Bee moves back and forth between England and Nigeria, exploring both countries from the points of view of its two narrators: Nigerian Little Bee and English Sarah. Little Bee gives us somewhat idealized glimpses of life in her rural village before it became a target for oil companies. Although the actual destruction of the village and the murder of most of the people are never detailed, the brutal rape and murder of Little Bee's sister on the Nigerian beach is.
Most of Little Bee's time in England is spent in an immigration detention center. She's only on the outside for a few days before she's deported. Through descriptions, and her imagined conversation with "the girls back home" (now all dead), Little Bee shares the wonder and the anxiety she feels about this new land. Sarah's own discomfort with her industrialized society, and her suburban neighborhood provide a viewpoint that contrasts and compliments Little Bee's.
Chris Cleave says that Little Bee "is a story of two worlds: the developed and the developing, and of the mutual incomprehension that sometimes dooms them to antagonism" (source). We'd say it's also about how Little Bee, Sarah, and Charlie cut through that mutual incomprehension. They find common ground that transcends cultural differences.