Be careful?

     When he got up from the table and reached for his hat, Bess turned around, a fork in her hand. "Borden, be careful."

    He walked outside in the bright morning sun and looked toward the McCoy house. How could he be careful when he had no idea who had to be careful of?

    Somebody in town wanted to kill him. Somebody in town was getting very, very worried. For somebody time was running out . . . somebody who had shot before, and would again, at any instant.

(from Borden Chantry, by Louis L'Amour)