"What Must Happen" is the second episode of Stationery Voyagers. It covers the continued quest of Mitchell Lomken and his late father's butler Eliot, while also giving us the origins of Arnold Rubblindo, Rhodney Antilles, the Xylien Society, the Imperial War of Markerterion, and General Bluque's secret partnership with the Mystery Wanderer.
We get a first glimpse into the affairs of Mantith's neighboring worlds, while Mitchell and Eliot back on Mantith seek to finish the delivery quest they started in "Scalding Inquiries." The motivations for the Imperial War of Markerterion are given, and we get to meet Alhox, Bluque, Pinkata, and the Mystery Wanderer for the first time. Arnold seeks guidance on what to do about Pinkella's disappearance. We learn about the Xylien Society for the first time, the Voyager program, and the recruits Rhodney and Oceanoe. Rhodney gives Oceanoe his backstory. When Arnold grows impatient with his family's unwillingness to help him find his missing girlfriend, he takes matters into his own phantomars. However, this leads to his involvement in a dangerous police chase that leaves him mortally wounded.
Arnold and his mother debate the ethics of artificial reincarnation and discuss Pinkella's disappearance. In spite his concern over Pinkella, Sally remains apathetic and closed-minded. Worse, Pinkella's parents are also missing. Mitchell and Eliot prepare to deliver ten of the thirty books they brought over on the plane to Cal Bacon, but Daldonist spies attack and burn the house down. This is after the two had already narrowly escaped death during a terrorist attack on the airport. The pair survive the attack on their cabin and kill the assassins, but Eliot is wounded.
Meanwhile on Markerterion, Alhox and Bluque debate the details of the Imperial War of Markerterion that they intend to go forward with, after rumor has reached the other worlds that Markerterion may resort to war to end the threat of the Yehtzig Pirate League. Alhox finally agrees to Bluque's war plans, but puts Bluque in charge of handling most of the war so that Alhox himself can devote more of his time to handling Markerterion's domestic affairs.
Bluque meets behind Alhox's back with a mysterious Bedouin figure calling himself the "Mystery Wanderer." The Wanderer claims to want to help Bluque out, but Bluque is naturally suspicious and questions the mystical being's true intentions. The Wanderer assures Bluque that all is going according to plan and that what is about to happen is "what must happen."
In the Xylien Underground, two Pens named Rhodney and Oceanoe leave a room after a training exercise. They head to a leaner bench to talk, and discuss the mission they are on. They give their doubts to each other about whether or not their mission is feasible, and complain that neither yet knows who the ship captain will be. When Oceanoe asks Rhodney to give his story for how he decided to join, a flashback sequence shows Rhodney's past life as a daredevil in the Daredevils 4U Association.
Rhodney is shown as being second in his sport only to the wild and rebellious Harvey Leadfort, with whom he is a part-time friend and part-time rebel. Internal spiritual conflict eventually drives Rhodney to search for answers outside of his daredevil profession, leading to him quitting and joining the Xylien Underground. A distraught Harvey searches for answers, but is deserted by his girlfriend Veronica and gives up on Rhodney.
As Rhodney finishes up his story, he begins asking Oceanoe for his story. Meanwhile, Arnold leaves early in the morning to investigate Pinkella's disappearance further. A known drug runner a few miles back begins talking with friends of his who work at Bubblespeck Gum, and they discuss over their cell phones their opinions of Corphel Frank's takeover of the factory.
Cops down on their luck and in need to fulfill their quotas catch a glimpse at the drug runner's car, and immediately begin a high-speed pursuit. The pursuit quickly gets out of control, and ends in Arnold being tragically flung off the road and into a Macadone's cactus. The police continue in pursuit of the drug runner.
- Rhodney's backstory was given only as a way to advance the story sooner. Originally, his backstory was going to be saved for an episode all its own.