It happened because she’d mislaid her postage stamps late on a Friday afternoon.
She’d used them that very morning. They weren’t in the book she had opened; they weren’t on the floor. They weren’t anywhere. Maybe she had posted them by mistake in the envelope she had mailed; picking them up underneath the papers she had posted.
Since she wanted to post some letters over the weekend, she got in the car to duck down to the stamp shop before closing time.
On the way she knocked a child off a bike. The child was killed.