If Not you then Who?: Who turned off the Lights? (Hardcover) (ISBN-13: 9781662967702)

The Sparks kids have a secret: they can travel back in time! But their adventures aren't just for fun-they journey into the past to save the world's greatest inventions.

In Who Turned Out the Lights?, Brooke, Noah, Graham, and Lily Sparks travel to 1880 to protect one of the most important inventions of all time: the electric light bulb. When the world suddenly goes dark, replaced by candles and gas lamps, the kids know their old enemy Emperor Entropy is meddling with history. He has stopped Thomas Edison from inventing the light bulb, threatening to leave future generations in darkness.

With the help of their scientist parents and their lovable robot dog, Chronos, the Sparks kids race to Menlo Park, New Jersey, to find Edison. But they discover he's abandoned the light bulb for a frivolous gadget. Now, it's up to the Sparks siblings to rekindle his spark of ingenuity before Emperor Entropy succeeds in erasing electric light forever.

Packed with adventure, humor, and real history, Who Turned Out the Lights? is the first in the new chapter book mystery series based on the best-selling If Not You, Then Who? non-fiction educational series.

Each story explores what life would be like if an important invention had never been created-while the Sparks kids show how curiosity, creativity, and courage can save the day.