Here are some titles of suspenseful books that I hope you will enjoy as much as you liked The Client by John Grisham:
The Face on the Milk Carton by Caroline B. Cooney.
A photograph of a missing girl on a milk carton leads Janie on a search for her real identity.
The Trial by Jen Bryant.
Living in Flemington, New Jersey, in 1935, twelve-year-old Katie Leigh Flynn describes, in a series of poems, the effect on her small town of the ongoing trial of Bruno Hauptmann for the kidnapping and murder of Charles Lindbergh's baby son.