The premiere of FBI: International Season 4 kicks off in the vibrant city of Los Angeles, introducing us to Supervisory Special Agent Wesley "Wes," whose romantic entanglement with fellow agent Ella is anything but smooth sailing. Mike, Wes' steadfast partner, perceives their relationship as toxic and urges Wes to sever ties. Yet, Wes remains in a state of denial, blind to the truth haunting their partnership.
On the professional front, Mike and Wes dive into the depths of a robbery ring case, convinced they're closing in on the culprits. However, their superior remains skeptical, instructing them to tail the suspects without confrontation. The tables turn abruptly when the gang audaciously attempts a daylight kidnapping, prompting a fiery shootout. Wes hastily requests backup, but amidst the chaos, Mike sustains a gunshot wound and is hastily whisked to the hospital.
Wes' frustration boils over, believing that had their superior heeded their earlier backup request, the outcome would've been vastly different. Mike would still be unharmed, and the gang wouldn't have slipped through their fingers. Once his emotions settle, Wes visits the deceased suspect he shot, discovering that his fingerprints aren't logged in the system. Facial recognition reveals the man as a Hungarian national on his second visit to the States. A closer inspection of the deceased's flight manifest unveils Vilmos, the shooter of Mike, among the gang members.
Given the gang's Budapest origins, Wes boards a plane to Hungary and reconnects with Vo, his former trainee and now a colleague. Although their past together might have harbored grudges, Vo assures Wes that her rigorous training under him was beneficial, and they're on solid ground. Eager to collaborate, she brings him to their headquarters, where curiosity piques among the team about Wes' identity. Vo introduces him as a crack case solver, albeit a bit of a protocol rebel.
Together, Vo and Wes storm the embassy, probing into how the gang members secured visas despite their criminal backgrounds. However, the trail runs cold as it seems someone cleansed their records. Meanwhile, Raines and Smitty pay a visit to Vilmos' mother, who's tight-lipped. She insists her son only visited America once and hasn't seen him for months, refusing cooperation and demanding they leave her be.
Moments later, she makes a mysterious call, followed by an incoming call from a blocked number that the team traces to Greg. A former convict turned mentor running a program for troubled youth, Greg surfaces with a link to Vilmos and the other deceased gang members who attended his program.
Without obtaining Smitty's consent, Wes decides to confront Greg, hoping to extract information from him. However, his visit turns out to be a waste of time, as Greg steadfastly asserts his transformation and denial of any involvement in forming an international robbery syndicate. Smitty lambasts Wes for his reckless actions upon discovering his unauthorized visit, emphasizing the crucial necessity of adhering to protocols.
Likewise, Vo sternly reprimanded Wes after the latter lost his composure with a contact in Budapest. This contact had insisted that the team cease their surveillance of Greg, citing the absence of official authorization. Subsequent to this confrontation, Vo and Wes retreated to the Embassy, anticipating a crucial meeting with Darlene, the visa facilitator. While they waited, Vo delved into Greg's prison psychological evaluation, uncovering his difficulties in managing his anger. Regrettably, their hopes of meeting Darlene were dashed as she had already left for home earlier than expected.
Tragic news strikes as Raines and Smitty find Darlene deceased in her apartment. Wes and Vo confront Greg once more, suspecting his involvement in Darlene's demise. Wes attempts to provoke Greg, but the criminal remains composed and refuses to cooperate, insisting on his innocence and pointing the finger at Vilamos as the potential culprit.
In the midst of this turmoil, Wes receives devastating news about Mike's death, leaving him shattered. The team rallies around Wes to offer support and vows to seek justice for Mike. Meanwhile, Amanda uncovers evidence suggesting that Greg and his gang are utilizing remittances to funnel funds into the country, leading them to Boglarka, Vilamos' mother, who has been facilitating these transactions for Greg.
Upon realizing Greg's attempt to implicate her son, Boglarka betrays him and reveals Vilamos' whereabouts to the team. Vilamos attempts to escape, but Wes apprehends him. Vo momentarily fears that Wes might resort to violence, but thankfully, he restrains himself and arrests Vilamos instead. The team subsequently interrogates Vilamos and persuades him to testify against Greg, leading to Greg's arrest based on Vilamos' statement.
After resolving the case, Wes receives a heartbreaking call from Ella, who decides to end their relationship, recognizing it as unhealthy. Wes reluctantly concurs, and they part ways amicably. Later, Vo speaks with Wes, encouraging him to stay with the team and suggesting that, based on his experiences, he is the ideal candidate to lead the Fly Team. She expresses her desire to remain a case agent rather than transitioning to management and assures Wes that the team is united in their support for him to take the helm.
