 During the night , Sideshow Bob reaches the houseboat and cuts it loose from the dock . Bob then ties up Homer , Marge , Lisa , and Maggie , to ensure they will not interfere with his plan . Bob enters Bart 's room , ready to kill him . Bart escapes out the window and tries to escape , but he cannot jump off the boat . As a " last request " , he has an idea : he compliments Sideshow Bob on his beautiful voice and asks him to sing the entire score of the H.M.S. Pinafore , to stall for time as the houseboat floats to Springfield . After the performance , Bob advances on Bart again , but the boat runs aground , and Sideshow Bob is arrested , and the Simpsons return home . 
