|The following information is from the Adventure Time comic book series. It may not be part of the same canon or continuity as the animated series.|
Issue #42 is the forty-second issue of the Adventure Time comics. It features the additional story "Sir BMO" by Ian McGinty and Fred Stresing.
Finn and Jake are on the run, trying to figure out who on the inside framed them for the destruction of Peppermint Butler's secret security team.
Two vagabonds (the secret text calls them Berto and Paultacular) are in the Bear Kingdom getting a truckload of fish. One remarks that bears are too dumb to start a civilization, and the other says they're so dumb that they were fooled by their simple bear hats as disguises. The bears actually are not fooled and maul the two, leaving behind their skeletons. Finn and Jake, who saw this occur, enter the city in better disguises. A group of soldier bears walk by, causing Finn's hat to change his disguise to match their appearance. He and Jake follow them and come across a workshop with weapons the bears made.
Jake says they need to tell Peppermint Butler what they found, but Finn says they never got a communicator. Jake then stretches his mouth and an ear to Peps' tower and tells him the bears seem to be getting ready for war. Peps asks about the Olyphaunt Drive, and Jake tells him the King of Ooo has it and may be plotting something. Upset, Peps commands them to get the drive and return. The King of Ooo, now in the workshop, proclaims to the bears that they are mindless beasts who accomplished much under his reign, giving one a belly rub. Another bear who made armor says they aren't all stupid, but lies down for belly rubs anyway. The king tells everyone that Phase Two starts soon and goes to his throne room. He says to himself how tired he is from being with the bears, but their honey makes up for it. He notices two guards that he didn't call for, which are actually Finn and Jake.
Because there are no bears around, Finn's disguise begins to fail. The two try to keep up the charade with the king, which briefly works. Once Finn's disguise is completely gone, Jake grabs him and they escape, alerting the king that they were spying. Finn is unhappy that they didn't get the drive and that Peps will be upset, but Jake says it was good they got out and that it was Peps' fault the hat blew their cover. Finn suddenly realizes that his watch is missing as well. Jake tells him they'll just talk to Peps and everything will be fine, but then they see his tower get blown up by Finn's watch, indicated by the beacon. Princess Bubblegum sees this and believes Finn to have done it. She has also seen footage of him and Jake saying things related to killing Peps. In the final panel, the still-living skeletons of the vagabonds state their pain and make a joke about it.
Finn and Jake are looking for BMO so they can play a video game. They can't find them in the house and decide to wait until they come back. BMO is at a lake poking a frog with a stick, asking if he has tadpoles. The tadpoles come out and BMO starts naming them. A princess of the lake appears, mistaking BMO for a warrior and asking for help. BMO thinks she is the tadpoles' mother. She angrily responds that she's a princess, and BMO lists some of the princesses they know. Regaining her composure, the princess again asks for BMO's help, and they accept. The princess then prepares to get a sword. BMO says they aren't allowed to touch swords, but they are allowed to touch the stick. The princess ties a cattail to the stick and knights BMO, who names the "sword" Frog Poker. The princess asks BMO if they're ready for the first task, and BMO asks for a sash, which the princess gives them. She tells BMO to gather a band of warriors and fight the scourge of the Lake Kingdom, the Mean-Mug Skullbiter. Just when she is about to send BMO off, she finds that they are gone. BMO has returned to the tree fort and is with Finn and Jake. Jake asks how they got the sash, and they say it was for bravery.