The Convicts by Iain Lawrence

Tom Tim's father, Captain Tim, has been taken to debtor's prison in London because of the debt he owes to the calculating Mr. Goodfellow. His mother has been paralyzed with grief from the loss of his sister, Kitty, in a drowning accident years before and isn't much help. It is up to Tom to find a way to pay the family's debt. So Tom leaves home to find away to make things right for his family. Tom finds himself down by the river while contemplating what he should do next, he notices a blind man poking his cane in the mud to find coins. Tom decides to do the same and while walking barefoot in the mud finds a large diamond. The blindman laying claim to the area goes after Tom to get the treasure. Tom fights off the blindman and loses him on the streets. There he meets Worms who gives him a ride in exchange for some help with a job and a small payment. Worms is a grave robber and he needs help stealing a body. A body that turns out to be a dead ringer for Tom. In a rush to escape being caught at the grave, Tom leaves his coat with the diamond in the pocket. Events in the story escalate with Tom getting accused of murder and continually getting mistaken for someone called "Smasher". Who is Smasher and why won't anyone believe his story? How will he get out of this mess?