Barnett comes into Vincent Keller's cell with his partner, Agent Thomas, saying they're running some tests on orders from Agent Knox. Vincent agrees to come, but later finds out they weren't sent by Knox. Furious, Vincent transforms and reveals himself as a beast to Thomas & Barnett. They let him go, though, when he offers to kill Gabriel Lowan for them, who is trying to expose Vincent as a beast. Vincent later finds out Barnett & Thomas exonerated him, meaning they're legitimate government agents.
When Gabe tries to kill J.T. Forbes, Vincent's best friend, Thomas saves his life. Barnett tells Vincent he should've killed Gabe when he had the chance, or he could've had his exoneration taken away. However, in return, Barnett asks Vincent and Catherine Chandler to help them stop other threats that could be a lot worse than beasts. Vincent & Catherine hold off on giving them an answer.
Barnett still has Thomas track down Catherine, telling her to get Vincent to help them out with their case. Catherine refuses to tell Vincent unless there is legitimate proof that they need his help. Barnett, annoyed, tells Catherine that they owe Thomas & Barnett for saving J.T.'s life, but Catherine doesn't back down. Thomas then shows Catherine signs of someone experimenting on innocent people, and turning them into superhumans. Barnett says they're dying or killing other people, as result. He says they need Vincent's help in order to stop the experiments. Catherine still doesn't plan on helping unless they can give her something more.
Thomas & Barnett later call Catherine when they find a potential superhuman experiment, Tyler Zane. After talking to Tyler's wife, Barnett is convinced that he's an experiment, and tells Catherine they need Vincent to get involved. Before they can, though, Tyler attacks the three of them, and throws Barnett onto a nearby car, killing him instantly.