NCIS: Los Angeles may think that writers have forgotten about Callen's mysterious past, but next week's episode is set to prove them wrong.

As the 100th episode of the series, "Reznikov, N." is poised to drop some major reveals regarding Callen (Chris O'Donnell) and his family.

"Promised spoiler: GCallen discovers more of his history, in a big way EP.504-100 #staytuned #comingsoon #NCISLA," tweeted producer John Peter Kousakis.

'NCIS: LA' Season 5 Spoilers: Eric and Nell's Developing Relationship, Nell to Replace Hetty?

The quest to find answers regarding Callen's identity and history has been a recurring theme throughout the last five seasons of the CBS drama. While the season 3 episode "Lange, H" explained that Callen's grandfather, George, was an OSS agent based in Romania whose dealings with the Comescu family eventually led to the death of Callen's mother, Clara, little is known about the paternal side of his family.

From recent promos, it appears that the NCIS agent will come to face to face with the man who calls himself his father. Fans may be wary, however, of anyone who calls themselves Callen's relation. Season 1's "Callen, G" featured a woman who had spent the better part of her life masquerading as Callen's deceased sister.

"Anyone who has followed the Callen story, in his search for his identity to find out who he really is - to fill in the puzzle, he has that tea tin that sits on his mantelpiece and has little jigsaw puzzle pieces of his life in there - he gets to put another very, very significant piece of the jigsaw puzzle into that tea tin," said series creator Shane Brennan in regard to the milestone episode, according to Xfinity.

Meanwhile, Kousakis has revealed that Callen will receive help from a former nemesis.

Check back all this week for news on how the 100 th episode will effect Deeks (Eric Christian Olsen), Kensi (Daniela Ruah), and Assistant Director Granger (Miguel Ferrer).

NCIS: LA airs Tuesdays at 9 p.m. ET on CBS.

Tags
NCIS: LA, NCIS: Los Angeles, CBS, Television