Dangerous Games — Carolyn Keene

AMERICA'S HOTTEST TEEN DETECTIVES TEAM UP IN A SPLIT-SECOND RACE WITH TERROR

An urgent message draws NANCY DREW and her friends to the International Championship Games in California. It seems a mysterious figure called the Black Knight wants to force star athletes off the track and into the hospital. But when Nancy starts to dig for clues, the young sleuth finds she is a moving target in a high-risk event -- where any mistake is fatal.

Meanwhile...
THE HARDY BOYS show up at the games to help beef up security -- and uncover a scandal. Along with acts of sabotage, there's evidence of illegal steroid use by certain athletes. But Frank and Joe's most critical problem is the Black Knight. The murderous phantom is about to deal a deathblow to the competition. And the brother detectives are top picks for the all-victim squad...