"Philo Vance: Man of Action," said nobody never. And yet Kidnap shows real signs of Van Dine's responding both to the changing times--friends, it's not the Jazz Age any more--and to the public's changing tastes, as Philo does much less sitting around pontificating and much more running around chasing bad guys. To accommodate this new, Action Philo, the plot is somewhat simplistic, featuring not only a purloined playboy but also a demand that the ransom be left at midnight in a hollow tree. However, Philo's newfound skills with a pistol are additions to his bag of tricks, rather than replacements for the tricks we know and love; rest assured that he retains every ounce of his customary implausible charm.