Yesterday I ran the second episode in my season of the Firefly RPG, titled "The Kill Switch." All the same players playing the same characters showed up as from my last session, right here.
In this episode, while Enzo was working on the compression coils, he accidentially triggered the intruder alert alarm on the Serenity; a routine problem, easy fix. The whoop whoop! of the alarm, however, turned out to be the subliminal activation code for the Kensington Protocol inside Q's head. Turns out what the Alliance did to Q, in addition to making him a killing machine, was they implanted this biological programming into his brain that, when he heard the trigger sound (in his case, a ship intruder alert signal), his programming would override his brain and he'd have to complete his mission.
His mission? Disable whatever ship he's on, including all crew within, then signal the nearest Alliance vessel to board it. If he can't disable them, "plan b" is to kill them and destroy the ship. Q's own survival was secondary to the mission.
So Q hears the signal, jump kicks a flustered Peaches, then disappears into the access chutes within the Serenity. The rest of the crew conduct a manhunt to find Q and bring him to heel before he can knock out the ship (and everyone in it).
Dr. Montgomery knows all about the Kensington Protocol. As revealed in three flashback scenes about his past throughout the episode, he used to work for the Alliance on a project to undo the Kensington Protocol from sleeper agents who were no longer needed after the war, so that they could live a normal life again. Dr. Montgomery knows that, in the event the Kensington Protocol is accidentially triggered, it can be deactivated through a "kill switch," a phrase of emotional significance about Q's childhood. All doc had to do was discover the kill switch, and the problem's solved.
As a failsafe for people to discover the kill switch, Q's brain has been altered so that he must truthfully answer all questions about his childhood. So while the crew is trying to hunt down Q and fix the ship as he damages it, Dr. Montgomery is communicating with Q over the intercom, learning about his childhood growing up and trying to discover the kill switch. Q couldn't say any of the words in his own kill switch, so Dr. Montgomery and the rest of the crew had to pay attention to any words Q was talking around and going out of his way to not say while answering the questions.
Like a good episode of Firefly, it came down to the wire. Q tried to enter the cockpit and fly the ship to the nearest Alliance cruiser, but in a spectacular fight scene with Sally, he escaped back into the vents. He was flushed out of the vents by a coolant spray that Enzo used to flood them, where he then donned an atmosphere suit, threw the other suits out into space, then evacuated the ship through the airlock. There, Q proceeded to use makeshift explosives and tools to blow off both airlock doors, which would have caused the Serenity to lose all of its oxygen and kill everyone inside. Without space suits, the crew had no way to reach Q outside the ship. All they could do was desperately assist Dr. Montgomery in discovering the kill switch before it was too late (they could still communicate to Q through the suit's comm system).
When a desperate plan by Jack and Enzo stopped Q from blowing off the airlock doors, Q then made his way to the outside of the cockpit and went to work on the cockpit exterior hatch. He was about to blow it off when Enzo, of all people, blurted out the kill switch "You are not a mistake!" Q snapped out of the Kensington Protocol, and they all lived happily ever after...for this week, anyway!