|Occupation||Men of Letters|
|Episode(s)|| 12.01 Keep Calm and Carry On|
12.02 Mamma Mia
12.04 American Nightmare
Mr. Ketch is an agent of the British Men of Letters.
As Lady Antonia Bevell tells Sam about how the British Men of Letters deal with monsters in the UK, we see Mr. Ketch being brought a recently captured vampire for disposal. As the vampire is laid out and restrained on a table, Mr. Ketch calmly walks to the table and decapitates the vampire. Later when Lady Bevell and Ms. Watt have hit a brick wall with torturing Sam, Ms. Watt suggests they bring Mr. Ketch. However, Lady Bevell is vehemently against bringing him in by stating that she doesn't want "that psychopath anywhere near [her]."
After Mick Davies collects Lady Bevell, the two argue about her failed mission. Toni feels that the Winchesters need to be eliminated. Davies assures her that if it comes down to it, he is prepared for that. He reveals he has sent for Mr. Ketch, who is shown packing cases with various weapons as he prepares to leave the UK.
While tracking the Winchesters, Mr. Ketch stops to inspect the Impala while the Winchesters are talking with the Peterson family, before driving off on his motorcycle.
When Magda Peterson's bus to California makes a pit stop, Magda steps to use the restroom and is followed in by Mr. Ketch, who attaches a silencer to his pistol. When he enters the restroom, Magda notices the gun in his hand, but before she can scream or do anything, she is shot dead. As Mr. Ketch is leaving the rest area, he receives a phone call from the London Chapterhouse and reports that he "cleaned the Winchesters' mess" and that "as suspected, they couldn't finish the job".
After Sam, Dean, and Castiel are stopped and held at gun point by the Secret Service. Mr. Ketch drives up to the scene. Casually exiting his car with a grenade launcher, he fires it at the Secret Service's SUV, blowing it up and knocking the agents unconscious. Telling Castiel to wipe their memories, he asks the Winchesters who is after them, noting the government plates on the cars. When Dean demands to know who the hell he is, Mr. Ketch introduces himself as Arthur Ketch, British Men of Letters.
That night, Mr. Ketch explains that his job is to "strongly encourage" the Winchesters' cooperation with the British Men of Letters. He was sent by Mick Davies after Sam called him and hung up, leading Davies to believe that the Winchesters were in trouble. When the boys are leery after dealing with Lady Bevell, Mr. Ketch has Castiel confirm that he's not lying. He shows them his arsenal of weapons, including a hyperbolic pulse generator, a device capable of exorcising a demon from its vessel. Recognizing its potential, Sam asks if it will work on an angel. Intrigued, Mr. Ketch asks what they have gotten themselves into, only to be told by Dean that if the British Men of Letters want to be trusted, they need to trust the Winchesters with the pulse generator, which Mr. Ketch freely gives up.