I don't have much enthusiasm for this. I can puzzle out the apparent contradiction that Maryann points out here...
My confusion is with different details: does the shade get in, or not? "Inside the doorway" conflicts with that unanswered door and that unrelenting lock.
...but in a poem this short I think the need to work out the logistics of the scenario is a waste of precious time.
All in all the scene seems too much of a stock one, the language too expected, and there is no pay-off at all. For me a sonnet is first and foremost a contained poem, and this one seems more like an introduction to something longer. The sonnet's sense of compression is missing here, and the arc of thought and description seems too languid for the form. In an effective sonnet I could imagine this entire poem taking up about two lines.
Nemo
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