Showing The Ever-Running Man by Marcia Muller

Sharon McCone is hired by her husband's security firm to track down "the ever-running man," a shadowy figure who has been leaving explosive devices at their various offices. She doesn't have to search for long. When McCone narrowly escapes an explosion at the security firm's San Francisco offices, she catches a glimpse of his retreating figure. The ever-running man is dangerously close--and anyone connected to the firm seems to be within his deadly range. To complicate matters, McCone is forced to question her intensely private husband, Hy, about his involvement in some of the firm's dark secrets. The history of corruption may jeopardize their marriage, but uncovering the secrets of the firm may be the only way she can save her husband's life, and her own.