After six episodes and countless wild goose chases, Reacher season 4 has finally revealed what was hiding on the USB. But you may be wondering what it actually is.
Warning: the following contains spoilers for Reacher season 4 episode 7. Turn back now if you haven't caught up, but make sure to read our spoiler-free Reacher season 4 review first.
At the very start of the season, we learned that just before Anna Merrick had committed suicide, she handed a USB drive to Reacher, which everyone seemed to be after, including the CIA, the FBI, and the Hoths. But since then, we never really knew the contents of the drive. Reacher and co had found a picture of John Sampson and his military buddies in a lab on base in Indonesia, but they didn't know what it meant. Until now.
What is the chemical toxin in Reacher season 4?
After Jacob Merrick saved Reacher and Tamara from Leo Ahlquist’s hired goons, the trio makes their way back to the scientist's office to interrogate him further. Ahlquist reveals that the photo contains the formula for a deadly chemical weapon that they were working on during the war as a defensive mechanism. Following Tokyo's gas attacks, the US wanted to find a way to protect the nation from possible future chemical attacks, so the CIA tasked Ahlquist and DARPA with creating the weapon so that they could then find the antidote.
So why are Lila and Amisha involved? Well, the CIA didn't want the trials, known as Operation Mongoose, taking place in the US. So the nation made a deal with Indonesian General Putra. The agreement was that DARPA would be able to work on the chemical weapon in Indonesia in exchange for Delta Force training the Indonesian troops. Sampson was part of Delta, but he didn't know the whole story at the time. In the back of the picture, we can see Amisha, who was working in the lab.
The reason why everyone was so hell-bent on getting their hands on the USB is that when Anna stole the files after being threatened by the Hoths, it tipped off the Department of Defense. In turn, the CIA and Sampson's men wanted the information out of the public eye. Whereas Lila and Amisha want to recreate the toxin to sell to worldwide terrorist organizations. But there is definitely a personal element in there on Amisha's side.
So what actually is the toxin? Well, the poison is made from the seeds of a native Indonesian plant, which Lila keeps in her bracelet. From there, the Hoths used a bunch of scientists and tech experts to crack the code, use the formula in the picture, and recreate the toxin. Lila's minions then found a way to make it airborne and cover a wide area in the hopes of "killing thousands," as Lila states. Reacher catches wind of their plan and sets out to find an event in Philadelphia that the Hoths may be targeting, eventually landing on a huge orchestral concert playing movie scores (including Mission: Impossible).
However, Reacher's hunch was wrong. The Hoths were actually targeting Sampson's party, sending in Tomas Waberi, whose ID was flagged earlier in the season, on a suicide mission. This makes sense, as it is revealed that Sampson was the one who carried out the hit against General Putra, whom Amisha worshiped. But before the toxin could be released, Sampson tackled Waberi and pushed him into a nearby body of water, ultimately sacrificing himself. With Sampson now gone and their plan foiled, we don't doubt that Lila and Amisha will try to release the weapon again. Let's just hope Reacher can catch up.
The Reacher season 4 finale lands on Prime Video on Wednesday, September 16. See our Reacher season 4 release schedule for exact timings, and keep up with upcoming shows on the way in 2026 and beyond.
