Animation. Dennis lives in Beanotown with Mum, Dad, little sister Bea and his pet dog Gnasher. Gnasher is more than a dog to Dennis; he is a kindred spirit. Whatever Dennis does, Gnasher does with him.
Together with their friends Curly and Pie Face, Dennis and Gnasher believe that the world truly is their oyster and that kids should make the rules. Not everyone agrees, including Mum and Dad. But Dennis and Gnasher are not going to let that stand in the way of their pursuit of fun!
Dennis discovers the legendary Pike of Beanotown Lake and sets out to capture it for his own menacing purposes. Dennis tries again and again to catch the pike, but fails miserably each time. Considering that it is just a fish, Dennis realises that the pike is a real menace. Dennis admires its menacing qualities and decides against trying to detain it. Then, on realising that Walter and his friends plan to give the fish over to science, Dennis has to step in to protect it.