In an unpredictable chain of events a mass flowering of the ancient New Zealand Beech forest leads to an excess of seed production. Mice and rodents take advantage of this abundance and numbers reach plague proportions. Incredible footage follows these rodents as they embark on a strange migration, attempting to swim across the expanse of New Zealand's rivers and lakes. There they fall prey to the largest predators in the lake - monster Brown trout. Gorging themselves on swimming mice, these fish become extremely aggressive and grow to epic proportions. For a fly fishing Angler who can tie a mouse pattern, this is the stuff dreams are made of. (40 mins)