Okay, so you're looking for summaries of 'Sandcastle'? The one by Pierre Oscar Levy and Frederik Peeters? That one's tricky. I love it, but it's definitely more niche than, say, 'Aama' or even Peeters's other work. A dedicated wiki is basically nonexistent. I found the most coherent plot breakdown was actually in the long-form review section on Goodreads, weirdly enough. Some users posted really detailed, almost scene-by-scene analyses that function like a summary.
Your other best bet is diving into the depths of comic book forums. I remember a thread on the Something Awful forums from ages ago that dissected the ending and the whole existential horror of the premise. Reddit's r/graphicnovels sometimes has posts about it, but you have to search specifically. The book's philosophical bent means summaries often get tangled up with people debating the themes, which can be annoying if you just want to know what happens.
Honestly, the lack of a clean wiki page kind of fits the book. It's opaque and leaves you to piece things together yourself, just like the characters on that beach.