Sherlock Holmes drew out a fine case, puffing leisurely at his calabash while pondering each clue until he deduced the culprit. Detecting, in the quintessential sleuth's day, required more than an agile mind; it took time. Of course, times change. Two of fiction's newest detectives have the necessary brainpower: they're young (in their 30s) African-American professionals (a professor and a doctor). These women, however, are so upwardly mobile that they can barely pencil murder into their crammed calendars.
The same profile fits their creators. Pamela Thomas-Graham, 33, a three-degree Harvard alumnus (B.A., J.D., M.B.A.), has taken a break from her career...