New York Times bestselling middle-grade thriller author Margaret Peterson Haddix returns to the Mysteries of Trash and Treasure series as Colin and Nevaeh unravel a mystery from the 1930s and explore the emotions associated with death and dying.

Colin and Nevaeh are great at finding things. After all, they found each other and became best friends—even though their parents are business rivals. They also found hidden boxes of secret letters, which led them to unravel mysteries about kids from the 1970s.

But when they started Mystery Solvers Inc., they didn't expect to be asked to find a ghost.

Ree recruits them to investigate a series of old, spooky photos left behind in her family's new house. The photos show a boy who looks totally see-through. And in some, he's in a coffin.

That's not so odd for Ree, who lives above a funeral home. But when Colin and Nevaeh start investigating, they discover other sightings of the boy—and other secrets Ree is hiding.

The more clues they find, the more they realize this mystery goes back to a time called the Great Depression. Will history, once again, help them solve the case?