In January 1999, Sarah Flannery, a sports-loving teenager from Blarney in County Cork, Ireland was awarded Ireland's Young Scientist of the Year for her extraordinary research and discoveries in Internet cryptography. The following day, her story began appearing in Irish papers and soon after was splashed across the front page of the London Times, complete with a photo of Sarah and a caption calling her "brilliant." Just 16, she was a mathematician with an international reputation. In Code is a heartwarming story that will have readers cheering Sarah on. Originally published in England and co-written with her mathematician father, David Flannery, In Code is "a wonderfully moving story . . . about the thrill of the mathematical chase" (Nature) and "a paean to intellectual adventure" (Times Educational Supplement). A memoir in mathematics, it is all about how a girl next door, nurtured by her family, moved from the simple math puzzles that were the staple of dinnertime conversation to prime numbers, the Sieve of Eratosthenes, Fermat's Little Theorem, Googols-- and finally into her breathtaking algorithm. Parallel with each step is a modest girl's own self-discovery--her values, her burning curiosity, the joy of persistence, and, above all, her love for her family.