I purchased the boxsets with season 1 and 2 together and season 3 and 4 together plus season 5 but the episodes aren't in order I want to follow the storyline. There isn't a season 5 just 4 they put most of season 4 on season 5. I purchased the seasons individually I had to order a multi region dvd player in order to play the seasons. I know these will be in order because on season 4 it says 4 discs but in the season 3 and 4 box set season 4 only had 1 disc. If you want to follow the storyline and watch the episodes in order buy them individually just make sure you have or buy a multi region dvd player.UPDATE Season 1 isn't in order but it's ok ill just have to watch them out of order hopefully only season 1 is the only one like this. Season 4 does have several episodes from previous seasons.