Bertha is making Jack-in-the-boxes that fail to stay inside the box! When Panjit loads the remaining toys to the dispatch department, he sees holes in the boxes. Roy, asking for a tin of glue, rushes off to tell Mr. Duncan about the situation. It's soon discovered that a mouse is venturing around the factory, chewing on things and creeping inside Bertha! So Mr. Sprot has to design a mouse trap...
