Danger Mouse's plan to hold a surprise party for Professor Squawkencluck is undone when the Baron releases killer birthday presents into the world.

Professor Squawkencluck reveals that she is testing Big Head - the artificially intelligent supercomputer that malfunctioned and turned on the agency last time. Squawk insists she has ironed out the glitches - and now Big Head has an exciting new programme: Portable Prison. Why waste all that time dragging criminals to prison, when we can simply take the prison to them! Big Head's ability to tap into surveillance cameras and computers worldwide means she can spot, locate and incarcerate all criminals instantaneously! Penfold's petrified. He once borrowed a pencil from a teacher and never gave it back. Big Head goes online and soon all our characters, villains and heroes, are locked up for ludicrous crimes. The two sides join forces to try and break out but Big Head is too smart for them. DM finally tricks Big Head into using Penfold's stolen pencil therefore committing a crime herself! Big Head melts down and the world is free!