[Urlik]

a secretary wearing a black long dress said

would read better as;
a long, black dress

but something far more sinister, some would probably have thought his business was malign.

would read better as;
but something far more sinister. Some would probably have thought his business was malign.
breaking it into two sentences adds more of a dramatic pause after sinister.

to his scary and mysterious employer.

would read better as;
to his mysterious yet intimidating employer.

searching for the escape routes. There was none,

should be;
searching for the escape routes. There were none,

chair in the front of the Syracuse desk.

should be;
chair in the front of Syracuse's desk.
or
chair in the front of Syracuse' desk.
depending on how you prefer pronouncing it. either is grammatically correct