sentences:  Manuel retaliates by having an associate plant a deadly "Bothrops atrox" viper in Wolfe's desk drawer, but Wolfe and Archie find and kill it.With Maria's cooperation, Wolfe and Archie arrange a robbery in the countryside to scare Anna into telling what she knows.The trick works, and she hands over documents proving that Manuel hired Carlo to build the driver that killed Barstow.