NCIS: Los Angeles's G Callen is closer than ever to finding out the truth about his father.

'NCIS: LA' Season 6: Tony DiNozzo To Visit, Shocking Air Date For Michael Weatherly Episode

The Special Projects agent has spent his life piecing together minuscule clues in an effort to understand where he came from. An orphan for as long as he can remember, Callen (Chris O'Donnell) will be antsy for answers as season 6 heads into "Kolcheck, A" and "Chernoff, K."

Unfortunately, Hetty (Linda Hunt) will have to remind him that the personal and professional don't mix (a lecture she has not, surprisingly, given to Densi).

'NCIS: LA' Season 6: What's In The Box? Shane Brennan Dishes On Densi Mystery

"Don't let the personal get in the way of the professional," Hetty warns in a preview for "Kolcheck, A."

"Kolcheck, A" will serve as Season 6's penultimate episode and, as you may have guessed, it will revisit the case of Arkady's missing oil tanker and his penchant for flaunting international sanctions. When the bodies of the crew are found adrift, Callen's team will find themselves investigating a rather explosive situation.

"Kolcheck, A" will air on May 11 while the season's finale, "Chernoff, K" will air on May 18.

Find out more when NCIS: LA airs Mondays at 10 p.m. ET on CBS.

Tags: NCIS: LA NCIS: Los Angeles television CBS