The episode description doesn’t actually confirm that this is Maria Bello’s farewell episode, but the actress was scheduled to appear in eight episodes of NCIS Season 18, and “True Believer” will be the season’s eighth, and it already sounds like the most Jack-centric episode of the season.
Jack and Gibbs traveling to Afghanistan because her name was discovered somewhere with a dead body and a group of kidnapped girls doesn’t really bode well for what seems to be Jack’s final case with NCIS.