Mr Boo comes from Wasteland, London's future world, and he drops into Mr Greenthumb's garden accidentally - thanks to a Witch who opens a time portal, just in time to help Mr Boo escape. But is she friendly? Somehow the monsters pursuing Mr Boo for his seeds have managed to jump through the portal after him. Despite the troubles that ensue, together, Mr Boo and Mr Greenthumb begin to learn the secret of the power of Mr Boo's magic seeds, and with the help of Betty, the garden gnome, who is boss of the underground compost works, Mr Boo begins to learn the power of compost. With help from some rather spoiled talking plants, some animated mushrooms and some magical animals, Mr Boo begins his adventures, and learns the first steps in land reclamation through helping to heal an Ear of Corn...