August is nine years old, and dreams of becoming a scientist. This is a dream that will never come true, because August is dying. The only dream that's left to him now is that of reaching his tenth birthday, on the last day of the month he was named after.

Yet on the eve of that month, August gets two surprise visitors: time-travelling ravens Muninn and Huginn, come out of Norse mythology to bring him the science that he loves. On each of the final days of August, the birds take him back through time to an event in science that happened on that day - the writing of the Einstein-Szilard letter; the discovery of the first Neanderthal grave; helium and Hiroshima and hot air balloons...

August comes to understand that these trips into science aren't simple kindnesses. They're ways for him to come to terms with his own death, to make peace with his mortality. And, if Muninn has her way, they'll give him a chance to cheat death after all...