Ms. Dumas was the new journalism teacher at Neptune High before she died in the Neptune High Bus Crash. She was the chaperone on the field trip.
Before the crash, she had an affair with baseball player Terrence Cook, who was engaged. She followed him to Neptune and told him to end the engagement or she would, which unfortunately she does. She also blackmailed him into continuing their relationship by using her knowledge that he threw a game to pay off his gambling debts. This becomes a possible motive for Terrence to cause the bus crash.