Black Powder Hardcover - 2005

From the publisher

South Central
Los Angeles, 2010
Fourteen-year-old Langston Davis's best friend, Neely, has been shot and killed in a gang fight. Langston wishes that he could turn back the clock. But he knows you can't change history. Or can you?
When his science teacher invents a century-hopping time machine, Langston knows exactly what he must do: go back in time to stop the invention of gunpowder...which will prevent the invention of guns...which will stop Neely from getting killed.
Hijacking the time machine, Langston leaves a holographic "twin" of himself at home and bounces back to Oxford, England, in 1278, where he's in a race against time to stop the scientific "wizard" Professor Roger Bacon from sharing his new invention -- the Western world's first form of gunpowder. When Dr. Bacon is kidnapped by his archenemy, it's up to Langston and his new friend, Niles, to try to rescue him and destroy the formula for gunpowder. But is changing history really saving the world? Or is it just standing in the way of progress? Can Langston accomplish his mission and bring Neely back to life before he gets stuck in the thirteenth century forever? No matter how you look at it, it's going to be one heck of a ride through the dangereous hairpin turns of history and back to the future again!