Thought Control

 is a Fallout 3 quest that is added to the game with the Point Lookout add-on.

Talk to Desmond
When you talk to Desmond about Calvert (the brain that you spoke to), he tells you about his past with Professor Calvert and the Calvert family in general. He then tells you to plant a jamming device on the boardwalk Ferris Wheel that will disrupt the messages that Calvert has been trying to send throughout the Point Lookout area. Once you near the Ferris Wheel, you can hear Calvert’s voice trying to persuade you to destroy the device that Desmond gave you.

Plant the Jammer, or Not

 * Destroy it, and Calvert gives you a little present called "death" when you meet him in the laboratory. Well that’s what he calls it, but whether or not it actually happens depends on you. He will send a bunch of robots out to kill you and you can decide whether or not you die. Smashing the glass tube containing Calvert's brain will kill him and cause all of the functioning robot's heads to explode.
 * If you choose to plant it on the Ferris Wheel, you will immediately be attacked by Tribals who come at you from the ground and are sniping at you from the rooftops. All the while having Calvert cursing both you and Desmond as the signal gets cut out. Kill them and then make your way to the Mansion.

Return to Desmond
When you try to approach it, it immediately explodes and parts of the house go flying everywhere as you knocked down to the ground from the shock wave. Once you stand back up, walk to the middle of the house and find Desmond in his fail-safe shelter. He begins to tell you how pissed he is after finally realizing how close Calvert was (After tracing the broadcast signal) and the deaths of his dogs. He then states that the 200 year long feud between him and Calvert is going to end right now.