"Gulf" is a science fiction novella by American writer Robert A. Heinlein, originally published as a serial in the November and December 1949 issues of Astounding Science Fiction and later collected in Assignment in Eternity. It concerns a secret society of geniuses who act to protect humanity. The novel Friday, written in 1982, was loosely a sequel. Story The story postulates that humans of superior intelligence band together, and keeping themselves genetically separate, create a new species. In the process they develop into a hidden and benevolent "ruling" class. The story invokes the notions of the General Semantics of Alfred Korzybski and the work of Samuel Renshaw to explain the nature of thought and how people could be trained to think more rapidly and accurately. The material on human intelligence and self-guided evolution is intermixed with a more standard "secret agent" adventure story. The "nova effect" can initiate a chain reaction that can consume an entire planet. Mrs. Keithley, one of the richest people in the Solar System, wants to use it to blackmail humanity, so she can rule from her home on the Moon. "Joe" is a secret agent who is tasked with getting the microfilm containing the only documentation of the effect. Returning to Earth, he is captured and finds himself confined with a man who calls himself "Kettle Belly" Baldwin. Using only two packs of playing cards to encode words, they communicate while under observation and plot their escape. Afterward, Baldwin introduces Joe to his group of intellectually superior individuals and trains him in their advanced techniques of thought, even attempting telepathy. Baldwin reveals that he and his group work to keep dangerous science and technology out of the hands of normal humans. The nova effect was discovered by Baldwin and implemented by his own people as part of an attempt to prove it could not be done. Joe meets Gail, another agent, with whom he falls in love. Baldwin receives a warning that the nova effect is set to be triggered on Earth, but the triggering device is on the Moon. Joe and Gail are sent to disable the trigger so the device on Earth can be neutralized. Gail has to get the remote control from Mrs. Keithley while Joe is charged with disabling the transmitter. The situation becomes desperate. Joe and Gail unexpectedly achieve telepathic rapport. Gail kills Mrs. Keithley, but is trapped with no