Hotline to Danger — Carolyn Keene

When there's trouble in River Heights, Nancy answers the call.

Nancy has volunteered to work the phones for the Help Is Here teen hotline--a crisis-control center for those with troubles at home, at school, in love. But she receives one call that requires more than a sympathetic ear. An anonymous female voice directs Nancy to a deserted neighborhood, where she finds the body of Paul Remer, another volunteer at the teen center.

Nancy knows that more is at stake than solving the case. She could also save a life. For the murderer has one chance to escape detection: get to the witness before Nancy does. But to find the killer, she must first identify the caller, and time is rapidly running out -- not only for Nancy, but for the girl on the other end of the line.