Чтение и письмо: повествование с предысторией (Past Perfect Simple и Continuous)

The key
When Maria finally found the key, she had been searching for nearly two hours, and the last bus had already gone.
She had moved into the flat only three weeks earlier. Up until that evening, everything had gone smoothly: the neighbours were friendly, the landlord had fixed the heating beforehand, and the walk to the station took eight minutes. What she hadn't noticed was that the front door locked itself.
That evening she had gone out to put the rubbish in the bin at the end of the path — thirty seconds, no coat, no phone. A moment later she heard the click. She stood on the step in the cold, staring at a door that, as far as she knew, could only be opened from the inside.
For an hour she tried everything. She rang the neighbours' bell, but they had gone away for the weekend. She walked to the corner shop, only to find it had shut at nine. She had no idea where the landlord lived, and his number was in the phone on the kitchen table.
It was then that it dawned on her: on the day she had moved in, the landlord had mentioned a spare key. «Under the third pot,» he had said, «in case you ever lock yourself out.» At the time she had laughed. Presumably nobody ever did.
There were seven pots along the wall. Sure enough, under the third one — the third from the gate, not from the door — was a small plastic bag. Inside it was the key.
When she opened the door, the clock said eleven. The rubbish, she noticed, was still in her hand. She had been carrying it all along.