The Shadow Tracer by Meg Gardiner

The day has come, as Sarah Keller knew it would.  For the past five years, she and her daughter Zoe have lived quietly in Oklahoma, far from her California home.  She fled there with Zoe when her sister, who is Zoe's real mother, was murdered by a religious cult.  When Zoe is in a bus accident and taken to the hospital, a fact that Sarah never knew is revealed.  She was given a microchip when she was a little baby and it reveals that Zoe's parents are not Sarah, which opens up a can of worms.

The police and social services are hesitant to turn Zoe back over to Sarah.  There is talk of putting her in the foster system until it can be determined whether or not Sarah is her legal guardian or a kidnapper.  Worse, the FBI are soon involved as they see Zoe and Sarah as their best bet to infiltrate and destroy the cult, which deals drugs for money to fuel their cult.  The cult also soon finds out what has occurred which sets their assassins on Sarah and Zoe's trail.

Sarah knows she must hit the road again.  Five years ago, she was helped by a US Marshal who sent her into hiding.  Now she reaches out for his help again.  Michael Lawless helped Sarah then without telling his superiors.  Will he risk his career to do so again?

Meg Gardiner has written a tense, jet-propelled thriller that will have the reader anxiously flipping pages to see what happens next.  Sarah is a real character, one that readers can imagine themselves being.  She is helped along the way by a woman who runs a skip-tracing operation, a nun who knows her way around guns and by Michael.  The villains are some of the scariest this reader has encountered and the maniacal determination of the FBI agent who is determined to bring Zoe in regardless of the cost in human life is implacable.  This book is recommended for mystery readers.