From: Themis Matsoukas on
> I don't think the O.P. had in mind asking for a fix.
> I think he was, in
> essence, trying to create a pure function with
> Block...
>
> f = Block[{n = 2}, #]&
>
> ... and then trying to evaluate that with argument
> Plot[n x, {x,1,2}].
>...

Then, the answer is

Block[{n = 2}, # &[Plot[n x, {x, 1, 2}]]]

Themis