The mysteries are already piling up for NCIS: Los Angeles' season 7.

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The CBS drama ended the sixth season finale with a major bombshell - Callen's (Chris O'Donnell) dad is alive and well - and that shocking reveal will come into play as the OSP team moves to close some longstanding character arcs.

"There's been so many storylines that they planted little tidbits over all the seasons, they're finally starting to harvest all those old storylines," O'Donnell teased, according to Extra TV. "So there's great stuff coming in the future."

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While Callen's quest for his father is certainly the series' most complicated through line, Deeks' (Eric Christian Olsen) IA investigation is the newest. It seems viewers can expect developments on all fronts when NCIS: LA's summer hiatus comes to a close.

"This is the first time, at the end of season 6, that we didn't have a 'To Be Continued' situation, but they sort of opened so many doors of things that need to be answered for the next season that it's going to be really exciting," actress Daniel Ruah told Extra TV, indicating that the events of "Chernoff, K" will not soon be forgotten,

Find out more when NCIS: LA returns to CBS this fall. Click the video below to see a preview for the series' latest episode.