They set out to capture spiders, etc., but accidentally let the creatures loose in the house, which of course results in much screaming and jumping up on tables on the part of Aunt Sally.
Jim is all, "Hey, stop putting live animals in bed with me," but Tom is having none of it.
Three weeks later, they have finally sawed the leg (unnecessarily) off the bed (which was a better alternative than sawing off Jim's leg), and nearly gotten sick from eating all the sawdust in order to hide the evidence.
Don't try this at home.
Meanwhile, Silas has been writing letters to the supposed owners of Jim (based on false information from the king).
Because he hasn't gotten any responses, he starts advertising around to stir up some interest.
Huck realizes that they have limited time before the news reaches Miss Watson back home.
Tom, ever helpful, writes a "nonnamous" letter to the Phelps family that reads, "Beware. Trouble is brewing. Keep a sharp lookout."
Sure, that should help things.
Then they draw a skull and crossbones on the door in blood, which understandably freaks the family out to no end.
On the night the boys are planning to steal Jim, Tom writes a detailed letter identifying himself as a thief and declaring that his fellow-thieves are getting ready to steal the slave who is tied up in Silas's hut—all so that his escape will be more thrilling.