The angry Lia shouted loud enough to make Sanno follow her. He panicked because of her loud voice, and so he pulled over to the emergency lane, then clicked the hazard button. He already knew what she would do, so he ran out of the car after she got out, and followed her.
Lia was mad about Sanno using someone's feelings as a step towards his mission. It would mean that everything was planned from the start, that was why he kept on nagging the naive young scientist and showing off his killer smile!
"Lia! Wait!" Sanno called. He observed that she didn't even bother taking her luggage from the trunk, clearly because she's very emotional. "Let me explain," he said, pulling her arm to make her face him.