When a former member of the Irish Republican Army turned U.S. citizen is shot while in London with his son touring youth football academies, Smitty and the Fly Team work to hunt down the people responsible as the group becomes increasingly violent. While in London, Smitty pays a visit to her mother who she believes can help the team locate an old family friend who may have a connection to the case.

The Fly Team heads to Oslo when they are tipped off that two Norwegian prisoners are being held in Russia.

The team investigates an American citizen who is proclaiming his innocence after seeking sanctuary at Madrid’s U.S. embassy while still covered in the blood of his murdered Spanish boyfriend. Also, Vo and Raines continue to grow their friendship.

The Fly Team discovers they’re on the trail of a serial killer, taking the investigation, and Mitchell, to Japan to put an end to the international killing spree.

A member of the Fly Team goes missing as the hunt for Greg Csonka continues in Paris. Meanwhile, Vo’s life hangs in the balance after being shot.

The team investigates the death of an American lawyer working out of Budapest, Hungary, after his is killed by a car bomb; Kellett begins to grow close to Hungarian lieutenant Benedek Erdős as the critical case progresses.

The team and Smitty head to Morocco when a commercial aircraft flying from New York to Athens is grounded and an American citizen on board goes missing; Kellett's relationship with Erdős continues to blossom.

The Fly Team lends a helping hand to the Hungarian National Police when one of their police officers is accused of murdering a couple in Budapest; Kellett questions her relationship with Erdős.

The Fly Team heads to Vienna to find the culprit of an acid attack on a rising American prima ballerina. Also, Smitty receives some troubling intel from a familiar face.

The team jumps into action to protect Forrester when a Russian hit man seeks revenge on him; Raines is sent into a tailspin when someone close to him is taken.

After an American tourist is killed while visiting Stockholm with his girlfriend, the Fly Team must work together to take down a Swedish group responsible for the hate crime.

After a cybersecurity expert robs one of Switzerland's largest and most secretive banks, the Fly Team is called to track down the fugitive. Also, Smitty's loyalty is put to the test.

The Fly Team jets off to Portugal when the daughter of a prominent American hotelier becomes the primary suspect in the murder of an employee. Also, Raines becomes concerned about Vo.

When a Russian missile is stolen and put on the black market in Budapest, the Fly Team must secure the weapon before a mysterious American arms broker delivers it into the wrong hands.

After a U.S. intelligence negotiator goes missing and her ransacked Paris apartment is discovered to be covered in her blood, the team is on the clock to find her before the country's nuclear secrets fall into the wrong hands. Also, Forrester finds himself drawing certain parallels to his mother's disappearance.

The Fly Team works to hunt down the sniper responsible for killing an American during an attack targeting a biomedical lab in Belgium. Also, Jaeger clashes with her boss at Europol over her allegiance to the Fly Team.

The International Fly Team is called on when a young mother flees to Hungary with her son, after losing partial custody of her son in the U.S. However, after the boy is kidnapped from his mother in broad daylight in Budapest, the team questions which parent is the danger in the child’s life

The team investigates an American journalist’s death by poison after his attempt to meet with an anonymous source in Poland. Also, Kellett takes Forrester to task for being overprotective with her during the mission.

The Fly Team lands in hot water when Vo is found at the scene where a Hungarian gambling regulator was murdered.

When a private jet carrying American citizens is shot down outside of a small town in Poland, the Fly Team looks into the man who missed the flight. Also, Forrester is conflicted when he receives information from his mother.

When the abduction of an American architect in Rome appears to be connected to a brewing terror threat in New York City, FBI’s Jubal and Nina join Forrester and his Fly Team in Italy as they work together to find the missing American and shed light on the terrorists’ U.S. target. The crossover continues on FBI S05E17 Imminent Threat (II) and FBI: Most Wanted S04E16 Imminent Threat (III).

When an ex-FBI agent suddenly resurfaces in a brutal Tripoli prison, Forrester and Powell risk everything to go under cover as prisoners to break him out; the fly team adjusts to their new and improved HQ.

When an American family's lavish sweet sixteen celebration is cut short after the mother of the birthday girl is found dead near their European estate, the Fly Team heads to Monaco to find the woman's murderer. Vo begins seeing Raines in a new light.

The Fly Team heads to Bulgaria in search of a wanted criminal who is exploiting underage American girls. Meanwhile, Raines becomes curious when Forrester asks him to keep an eye on Powell.

When a disgraced former U.S. cabinet member is arrested in Vienna, the Fly Team is sent to investigate whether he and his assistant were peddling classified government documents. Powell struggles as he is forced to stay behind on desk duty.