This is an example of a mini-series (a series with super short episodes) done mostly right. For some reason, most parts do not feel too hurried. The main weakness of many mini series is the pacing and erratic storytelling, and while Decline isn't entirely spared from it, I'm surprised by the plot development and character backstories.

I don't what the relationship between the two main characters is like in the novel, but I would classify it as bromance in the series. I was wondering whether to describe it as censored BL, but I think it is a case where we are left to imagine things if we want to but there isn't really that much BL innuendo. Sui Han Bai realizes that Su Chengxi is someone he has known since his childhood days quite early on although Su, who has lost his memory does not realize it till much later. We see Sui's devotion to Su when he blocks an arrow shot at Su with his own body and even in his semi-conscious state, calls for Su to stay safe.

The story unfortunately does seem incomplete, but to its credit, the series does have at least a tentative happy ending for the main characters and does not end with a silly cliffhanger when there may never be a Season 2. There is potential for a Season 2, but Season 1 at least ends satisfactorily.

Despite the synopsis, I think the series shows more promise if it is marketed as bromance rather than mystery/detective series because it thrives on our interest in the characters, and the mystery aspect leaves too much unaddressed.