Try not to panic. Have you asked the woman downstairs if she's seen Sonsy? And I know you've checked every closet and nook and cranny that she could have gotten into so I don't know what else to say except keep hoping.

Once, along time ago, Tubby didn't come out when I came home from work (he was usually waiting right by the door). I did the same as you, shaking his treat can, calling for him. A couple hours went by and he still didn't come out. I started to panic too, and called my boyfriend at the time. I was convinced something had happened during the day and Tubby was dead somewhere. Well, 5 minutes after my boyfriend showed up, he came up the stairs with Tubby in his arms. He had been sleeping behind some boards in the basement and for some reason hadn't responded to all my calls - or the treat can shaking. I was so mad at him, but yet so thankful to have him back, which I'm sure you're quite familiar with that feeling.

I know it's kind of late so you can't ask neighbors if they've seen Sonsy, but keep jingling her fishing pole and calling for her and hopefully she'll show up soon.