0pt0, if I have understood you correctly, you have done everything except identify the cell with the right abbreviation, carry out the revealed instruction and draw the shapes. There is only one cell that makes a word or name when combined with the seven large letters. There are two obvious ways of carrying out the instruction and one of them resolves the unusual cell in 10 down. The shapes (or lines) make an object related to the work's title. If you can't identify the work, try googling the two protagonists and the title of the puzzle.
And that, unless I too am missing something, is it.