In her third novel, Edgar-winner Theresa Schwegel turns in an intense look at obsession as she explores a cop whose career and mental health are about to implode while his fragile family steadily falls apart.

In “Person of Interest” (Minotaur/St. Martin’s Press, $24.95), Schwegel keeps the plot on a steady keel as she gracefully incorporates the police procedural and a story about domestic life into a cohesive, riveting novel.

Chicago police detective Craig McHugh is deep undercover as he investigates a powerful Chinese gang’s drug trade. Each night he plays cards with the gang members, gaining their trust. But his bosses don’t believe he’s getting anywhere, reassign him and cut off his funds. Craig is so fixated on the case, however, that he won’t stop the investigation and begins using his own money.

Craig not only can’t see the danger he is in, he doesn’t realize how his neglected family is disintegrating. His wild daughter, Ivy, is experimenting with drugs – supplied by the same gang Craig is investigating. His wife, Leslie, believes Craig is having an affair and starts what seems like an innocent flirtation of her own.

All that any of these people want and need is a little respect. As Craig’s job overlaps into his personal life, he and his family must find a way to survive.

Schwegel blends the family’s story into a thrilling tale punctuated by brisk action and believable characters.

When violence enters “Person of Interest,” the scenes are brutal and frank, but never gratuitous.

“Person of Interest” shows why Schwegel has become an author to watch.