Thriller fans will welcome Roberts's latest: Once again, children face danger without adult protection. Left in the charge of a disagreeable, meddling grandmother while their mother's away on business, Vickie (13) and her little sister Joanie run away from their Washington home to Dad's in northern California—only to find him missing, with clues in his apartment suggesting foul play. Staying on alone, the girls—and Dad's 15-year-old neighbor Jake—become embroiled in intrigue involving impersonation, missing union records that point to embezzlement, and violence. All ends well when Vickie finds the records, Dad is located, the culprits are caught, and (with Gram's imminent departure) even parental reconciliation seems likely. Unfortunately, though it's well plotted and paced, the novel's characters are unsympathetic. Vickie's first-person voice is often whiney or gratuitously violent (to Joanie: ``...help me pick up this place or I'll beat you up''; referring to Gram, ``I wanted to hit her''). Still, the stark realism adds to the suspense; the story works. (Fiction. 8- 12)