Last night on NCIS, the focus was on Tony DiNozzo and his lack of sleep. After being awake for days, he thought his mind was playing tricks on him when he glimpsed an informant from his BPD past.

In between flashbacks 15 years prior and the present, the question was what was keeping this very special agent awake, and whether he'd finally put his mind to rest after a tumultuous few months.

Check out our NCIS review for a full rundown on "Once a Crook."

Looking ahead to next week's episode, NCIS partners with the Coast Guard Investigative Service (CGIS) to investigate a suspicious explosion on board an oil rig.

Meanwhile, no one is safe from a mysterious prankster who is targeting the NCIS team. Who do you think it might be, and what kind of pranks are we talking about?

Check out the first CBS promo for "Oil and Water" below ...

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.