THIS is the way to launch a book!

Fowler gives Exposure to dangers of  ‘sexting’. Novelists are always urged to write about what they know. Author Therese Fowler has followed that advice with her third novel, Exposure (Ballantine, $25), in stores Tuesday. The plot centers on the red-hot issue of teens sexting, and Fowler’s knowledge is hard-earned.

In 2009, Fowler’s then-19-year-old son was arrested on a misdemeanor charge for e-mailing nude photos of himself to a 16-year-old female friend.

“I was astonished that simply sharing a photo of himself with a girl he knew could be considered criminal,” says Fowler, 44, from her home in Wake Forest, N.C. (The charges were dismissed.)

Fowler used the experience to write a Romeo-and-Juliet drama set at a posh private school in North Carolina…