The tracker arrived the next morning. Bridget spent most of the day in her garage, figuring out the fastest way to slap on the magnet. When night fell, she dressed in head-to-toe black, like a pedestrian with a death wish. She even put on Ajay’s socks, which were surprisingly thick and warm. For a few hours, she dozed on the couch, dreaming terrible dreams of hitting Joanne in the head with the bat, or even worse, of Joanne shooting her.

Finally, at two in the morning, Bridget got up, put on her black coat and gloves, and pulled a black neck gaiter over the lower part of her face and a black beanie over her hair.

After parking in the spot she’d picked out, she got out and immediately started to shiver. The forecasters were talking about snow, and she could feel it in the heavy stillness. The air was so cold each breath seemed to pull her lungs inside out. By the time she reached Joanne’s block, Bridget was shaking so hard she was afraid she’d drop the tracker. No matter how lightly she tried to walk, each footstep echoed hollowly. She kept waiting for a dog to bark, a light to blink on.

But the world around her remained dark and hushed. And finally she was on Joanne’s block, and then just a few feet from her car.

Hunched over, Bridget scuttled over to the driver’s side door, which was the furthest from the house. Just as she’d practiced on her dad’s car, she slapped the magnet underneath the door frame. And then she was gone. She ran the last two blocks to her dad’s car.

Back home, Bridget couldn’t sleep. Ajay hadn’t answered her email. Nobody knew what she was planning to do. At best, Ajay thought she was mentally ill and the police thought she was an obsessed loser. But in her heart she knew she was Bob’s only chance.

At four A.M., when she still couldn’t sleep, she pulled her laptop onto her bed and wrote Ajay another email, telling him what she was planning on doing and giving him instructions on how to use the tracker. Would he just shake his head, chalk it up to more proof she’d fallen down the rabbit hole, and then hit the DELETE key?

Finally, she was able to sleep. When she woke up, the light in the room told her it was late morning. Before getting out of bed, she went to the tracking page.

Joanne was already on the move. Bridget’s heart kicked in her chest. Should she run to her car, start following now? But, she reminded herself, that was what the tracker was for.