The donor

Just after her sixteenth birthday, Will's daughter, Georgie, suffers kidney failure. She needs a transplant, but her type is rare. Will, a single dad who's given up everything to raise his twin girls, offers to be a donor. Then his other daughter, Kay, gets sick. She's just as precious, her kidney type just as rare. Time is critical, and Will has to make a decision. Should he try to buy a kidney? Should he save just one child? If so, which one? Should he sacrifice himself? Or is there a fourth solution - one so terrible it has never even crossed his mind?