The Butterfly Girl by Rene Denfeld

Naomi's job is locating missing children, but she cannot find her own sister, lost for 20 years. She has no picture, no name, just a memory of a strawberry field at night and running for her life. Celia, a street child, has nothing but her hope in the butterflies that she imagines all around her on Portland, Oregon's dangerous streets, where young girls are going missing. As danger creeps closer, Naomi and Celia must ask themselves: can you still be lost even when you've been found? But will they find the answer too late?