Scumble by Ingrid Law

Scumble: Companion to Savvy

It's nine years after Savvy, and Mibs' cousin Ledge is on the verge of turning thirteen. More than anything, he wants the power to run like the wind. But when his birthday comes, he discovers that his savvy is actually making things fall apart. It starts out with small things, but then it gets worse. To top it all off, someone outside the family has witnessed his destruction. Now, in addition to trying to figure out how to control - or scumble - his savvy, he's got to worry about how to protect the family secrets. Over the course of one amazing summer, Ledge learns a lot about himself and his family, makes a new - and very unlikely - friend, and learns to appreciate his newfound skills.