In the tenth-season opener, Mac pursues unanswered questions regarding Webb's death and finds she's become the target of an assassin. Meanwhile, Harm and Bud are swamped by paperwork while the team waits for news of Chegwidden's replacement. Simon Tanveer: Ed Quinn. Laurie June: Adria Tennor.
Harm and Mac investigate a supposed friendly-fire incident in Iraq in which a marine was killed by a member of the Iraqi Civil Defense Corps, and both sides claim the other fired first. Lt. Ditullio: Jason Brooks. Sgt. Mark Burrell: Philip Anthony-Rodriguez. Cpl. Sheehy: Robert Blesse.
Harm is asked to investigate the case of a former Navy seaman (William Sadler) who may have unjustly spent the past 22 years in prison due to the military's negligence. Meanwhile, Mac and Bud handle a bigamy case. SecNav Sheffield: Dean Stockwell. Alicia Montes: Maria del Mar. Rachel Hanna: Ali Hillis.
The president nominates a hard Marine lawyer, Col. Gordon “Biff” Cresswell (David Andrews), to be Chegwidden's replacement. Also: Harm and Mac are sent aboard a destroyer to settle a dispute between the Navy and a Canadian fisherman. Sen. Kerner: Dr. Joyce Brothers. Adm. Kly: Andrew J. Robinson.
Maj. Gen. Cresswell, the new JAG commander, sends Harm and Mac to Baghdad for the court martial of a sergeant (James MacDonald), whose decisions while escorting a government official led to the man's death. Meanwhile, Turner, Roberts and Coates adjust to their new boss. Col. Lewis Atwater: Michael Gaston. Brad Holliman: Thomas Vincent Kelly.
Mac and Turner face off in the case of a Naval Academy sailing instructor (Christopher Shyer) charged with dereliction of duty when one of his crew is lost after the instructor decides to sail into a storm. Bud's brother Mike (Michael Bellisario) testifies for the commander. Midshipman Dupree: Vicellous Shannon. Lt. Brendan Slattery: Colby Donaldson.
Mac and Harm are sent to Guantanamo Bay, Cuba, when three MPs are charged with the abuse of suspected terrorists at a detention center. Meanwhile, Bud is arrested and tried for striking a man who threatened Mikey. Mikey: Michael Bellisario. Cresswell: David Andrews.
A friend (Alex Breckenridge) from Coates's criminal past shows up asking for a place to stay and assuring Coates that she's given up her old ways. Meanwhile, Bud intervenes on behalf of a Naval aviator who landed in trouble for giving flying lessons to her father, a civilian, after the man bought an F-18. Cdr. Collins: Frederic Lane. Det. Morris: John Cothran Jr.
Harm and Mac work with the FBI after a Navy commander, who's one of the government's top researchers in bio-weapon defense, vanishes, abandoning his car on a bridge. Meanwhile, Bud investigates a woman marine's petition to box with men in a military competition. Dr. Sperling: Bruce Davison. Marta: Victoria Tennant.
Mac's Christmas Eve car accident and its aftermath are interlaced with flashbacks of a discussion with a psychiatrist (Barbara Eve Harris) about Mac's relationships, particularly her connection with Harm. Mrs. Porter Webb: Claudette Nevins. CPO Duca: James Moses Black.
Harm is sent to California to investigate the unexplained crash of an F-14 near an elementary school. Meanwhile, Bud has a rough time in his anger-management class. Sgt. Willard: Allison Gammon. Stan Coffle: Dave Florek. Lt. Korsky: David Goryl. Lt. Graves: Jordana Spiro.
Coates becomes a juror on the case of a Navy officer accused of murdering a civilian over the love of a fellow officer (Dominique Swain), and Harm defends while Mac prosecutes. Cdr. Pulone: Geoffrey Lower. Lt. Buckey: Carmella Riley.
Harm and Mac travel to Afghanistan, where they search for a renegade marine (Michael Rooker) who has formed his own group of fighters determined to find Osama bin Laden. The marine is accused of killing civilians and is slated for court-martial. Col. Phineas Burns: Clayton Landey. Sahiba Khalili: Luck Hari.
A Navy psychiatrist (Kerrie Keane) is accused of malpractice when a marine under her care is sent into action and killed. Meanwhile, Bud handles an age-discrimination case involving a Navy commander (Tony Denison). Bud: Patrick Labyorteaux. Harm: David James Elliott.
Harm is sent to the Persian Gulf when a non-combative fishing vessel is fired on, and he finds himself the subject of an investigation. Meanwhile, Mac defends a Marine who seized an Iraqi car. Gregory Vukovic: Chris Beetem. Harm: David James Elliott. Mac: Catherine Bell.
Mac and Lt. Vukovic (Chris Beetem) are sent to the Straits of Malacca to negotiate with a pirate (Orlando Pabotoy) who has boarded a Burmese cargo ship and taken the crew hostage. Meanwhile, the staff back home is introduced to Cresswell's ebullient wife (Mel Harris) and his daughter (Danneel Harris), who charms Mike Roberts. Adm. Lutarno: Tzi Ma.
Mac, Vukovic and Lt. Mayfield join Cresswell for a JAG conference in San Diego, where Mac and Vukovic also face off in the court martial of a marine accused of killing a Nicaraguan civilian during a humanitarian effort. Also: Harm faces a tragedy involving Mattie. Lt. Graves: Jordana Spiro. Lt. Mayfield: Meta Golding.
Vukovic is sent to Iraq to defend a marine (Chris J. Johnson) accused of killing an unarmed civilian in a mosque. Meanwhile, Cresswell asks Mac to talk to Cammie about her plans to leave the military. Maj. Atkins: Paul Schulze. Brad Holliman: Thomas Vincent Kelly. Capt. Ellis: Derek Webster. Lt. Vukovic: Chris Beetem.
Harm and Bud are sent to Oklahoma to assist the families of Marine reservists killed in a bomb attack in Iraq, and end up court-martialing the only surviving marine (Travis Brorsen). Meanwhile, Mac is sent to Iraq to investigate the bombing suspect (Homie Doroodian). Amani Al-Reza: Arminae Azarian. Col. Joseph Mazzone: Scott MacDonald.
Cresswell asks Vukovic and Lt. Graves to investigate when his brother (Joe Regalbuto) believes a soldier's remains found in Vietnam are those of a pilot who saved his life during the war. Their inquiry takes them to the South to find a relative of the unknown soldier for DNA confirmation. Etta: Gladys Knight. Lt. Graves: Jordana Spiro. Vukovic: Chris Beetem.
Harm teams up---and clashes---with Vukovic when they go up against Bud to defend a sailor (Joshua Harto) whose fight with a colleague proved fatal. Meanwhile, Mac defends a sailor who freed Navy-trained dolphins. And both Harm and Mac hear startling news regarding their careers. PO Sanhuinius: Nick Von Esmarch. Sgt. Androvich: Matt Sigloch.
In the series finale, Mac and newly promoted Capt. Rabb prepare to depart for new billets in San Diego and London, respectively, and are permitted to choose their staffs from among their colleagues. Meanwhile, Vukovic is asked to investigate the case of an enigmatic Marine recruit (Zach Bostrom) who leaves his barracks at night to supposedly kill “the enemy.” Lt. Clarize: Boyette Tammy Townsend.