The Seven Deadly Sins the Movie: Prisoners of the Sky is a film based upon the manga and anime series. It is an original side story and as it was released after the second season, it assumes viewers has already watched that and know all the characters already. As a fully self-contained story, it lacks any sort of impact on the main storyline and is questionable on where it sits on the timeline either. Meliodas and the Seven Deadly Sins are finding food to prepare for the King's birthday when they stumble into a lost clan who lives in the sky. Coincidentally, it is at this time that some outcasts of the Demon Clan, known as the Six Knights of Black, decide to attack this town in the sky. The Six Knights were initially introduced as even more powerful than the Ten Commandments but considering the ease at which even Meliodas alone can hold back the six before the rest of the Seven Deadly Sins arrives, the claim is questionable. Prisoners of the Sky is pretty much a fan service film in the sense that it allows us to witness big flashy battle sequences as our favorite character curbstomps the evil villains. In this aspect, it works well and the film contains some of the best battles we've seen of the series. The plot is definitely the weakest area with an extremely simplistic story that lacks any sort of surprises. The usage of characters that are near clones of Meliodas and Elizabeth is cheesy. While it was never going to win any awards or significant amounts of praise, Prisoners of the Sky is a fun film for fans of the series.