Enigma

Fornell and Gibbs clash when it is discovered that a marine colonel, William Ryan (Terry O'Quinn) who also happens to be Gibbs's former C.O has absconded from Iraq with two million dollars, and returned to the states under an assumed name. The FBI believe that he staged the ambush and stole the money for himself while Gibbs denies the claim, believing he's innocent. Ryan later contacts Gibbs, and explains that he has discovered a conspiracy to siphon funds out of Iraq for use on black ops. Gibbs is drafted in to aid in bringing down the conspiracy, and meets the Colonel's partner - a lieutenant named Cameron who had actually died in Gibbs's arms years ago. After being arrested for "pissing off the FBI", Gibbs and Fornell set out to discover the truth behind the Colonel's claims in a tense standoff. It is soon discovered that Ryan is suffering from paranoid schizophrenia and after the standoff ends, he is put into a mental hospital so that he can be treated for his mental illness.