Three teams compete to create a deluge of volcanoes, earthquakes and other tiny natural disasters in only three days.
Three teams create best sellers based on the books of Lawrence of Arabia, HG Wells and Agatha Christie, featuring Roman ruins, alien motherships and the Orient Express.
Three teams create a bucolic landscape of crochet trees, massive replicas of Kings Cross and St Pancras station, and a fiendishly technical haggis delivery system.
Three teams take a magical mystery train tour through the jungle, a historic flood and the centre of the Earth.
Three teams fight for a place in the final with their sci-fi displays incorporating miniature aerial acrobatics, towering peaks and space travel.
Only two can make it to the last stretch, and with a tough challenge on a fabulous fantasy theme to overcome, any team could find themselves on the next train home.
The semi-finalists offer up blockbuster layouts based on Harry Potter, Jurassic Park and James Bond. Plus there is a mysterious operational challenge to overcome.
Four finalists have three days to create miniature railway layouts that amaze, confound and delight. But who will take the prize?