NCIS partners with the Coast Guard Investigative Service 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.

The NCIS team is forced to re-examine a hit-and-run murder case when a former FBI agent turned lawyer confides in Gibbs that her client's confidential alibi is solid. Meanwhile, McGee grows suspicious of Tony's strange behavior.