The 90210 Season 5 premiere will feature one farewell and one return.

As previously reported, Justin Deeley (as Austin) will exit the series on the October 8 opener, while TV Line now confirms that Lori Loughlin will come back for an episode as Annie and Dixon's mother, Debbie.

The actress departed prior to 90210 Season 3 when the show shifted its focus entirely to its teenage leads, raising the question of why her character is returning now.

Will it be related to Dixon's Season 4 finale car accident? And could it possibly be for her son's funeral?!? Rob Estes, it should be noted, will NOT stop by as Debbie's ex-husband and Dixon's adopted father.

Take your best guess now as to why Loughlin will make this appearance and also take note: Carly Rae Jepsen will be performing on the same episode.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.