As for the PDF you were searching for, here is the best way to access the series officially:
PDF versions are often static and outdated. Official platforms release cleaned-up, high-resolution versions with accurate translations. Fan-made PDFs may have typos, missing sound effects, or improperly cropped panels. Shutline Ch1.pdf - Google Drive
Lezhin is the primary publisher for Shutline . As for the PDF you were searching for,
During their interaction, it is revealed that Joo-woon’s high-end vehicle is experiencing mechanical trouble. While Sol expects a sexual advance, Joo-woon observes something else entirely: Sol’s latent talent. It turns out Sol is a self-taught mechanical prodigy with a "shutline" (a term often referring to the contour lines of a car body or the boundary of a mechanism) intuition for how machines work. Lezhin is the primary publisher for Shutline
The inciting incident occurs when Sol’s path crosses with a sleek, expensive car and its even more imposing owner. Sol, in need of money, attempts to proposition the driver, assuming a transactional dynamic where he holds the cards of seduction.
Shutline Ch1.pdf - Google Drive