Ninth grader Will Tuppence is in control.

He plans everything obsessively, from the perfect stargazing night with his crush, Mi-Su, to the regular Saturday-night games of Monopoly with his friends. He's even planned his entire adulthood: career as an astronomer; mint condition, black 1985 Jaguar XJS/12; two kids. . . .

But everything changes the day Will learns one startling fact: protons—those tiny atomic particles, the building blocks to the building blocks of life—can die. The one thing that was so certain in this world to Will has an expiration date.

And Will's carefully planned-out life

Not so certain, either.