Prudence Varley would have seen a flimsy screen toppling over with a crash, revealing the lurker behind with his contemptuous smile.
"The Furnace"
Rose Macaulay
A "lurker" is someone who read without ever contributing.
"The Online World"
Odd de Presno
A timorous thing ran the innocent hind, When the wolf was the hypocrite fang under hood, The snake a lithe lurker up sleeve, And the lion effulgently ramped.
"The Complete Project Gutenberg Works of George Meredith"
George Meredith