If my wife was to call me when she was at or near the Canadian Tire store and did not .... my first thought would be .... she is taking a longer walk , not unusual for her
If I was becoming impatient or antsy I would try phone her (of course) .... but if she did not answer I would likely think she was in a dead-cell spot , or in a building that blocked the signal , maybe even in the CT store already. Or she accidentally turned her phone off . Or she forgot to charge it and the battery went dead.
If I had any feelings or emotions , I would be "ticked off a bit" because she left me pacing the floor waiting for her call. If I find out her daughter also tried calling at 9:00 AM and did not get a reply I would start to be concerned , but I would still just suspect it was a phone issue.
If I went for a drive to find her I would head toward the CT store because that is her most logical destination .... I would do a quick scout of the store to see if she was there. Especially the ladder department. We were going to buy a ladder that morning.
If I did not find her at the store , and if contact with family and friends confirmed something was not right , I would worry something happened on her walk , thinking maybe she got hit by a car or something , lots of intersections to cross , I would be tempted to call the local hospitals .
The last thing on my mind would be that somebody had snatched her away , mugged her , or assaulted her , this is a nice area of town on a bright Saturday morning , my fears would be accident based . If the hospitals knew nothing , I would try call the police , tell them my concerns , and ask them if there had been any accidents that morning .
Police know nothing , hospitals know nothing , still hope she makes it to the birthday party and has a good reason for getting us all worried. In the meantime I would keep checking if she had come home , check the store again , and drive the streets some more. At birthday party time is when I would hit the panic button and know something was seriously wrong.
EDIT TO ADD: ... I wish we knew how it actually played out that first hour of concern 9:30-10:30 , and if a missing person report was made as early as 10:30 , my hinkey meter goes off
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