In this sneak peek, Jimmy and Kasie dive into an untested scientific method they hope will uncover new clues about Parker’s missing mother—even if the odds are slim. In the upcoming episode, McGee and Torres race to recover a stolen truck full of toys for the Navy’s annual Christmas drive, Knight undertakes her first NCIS: Elite mission, and the truth about Parker’s mother is finally revealed. Watch NCIS Tuesday, Dec. 16 on CBS and stream on Paramount+.