Topo's ship is returning from few years long expedition into open space.Topo already dreams of landing, when something wents wrong. There is explosions, and smoke. Topo in the rescue capsula falls toward Earth, while the ship and all the results of the expedition burns up into atmosphere. Topo luckily lands, but... it's 400 years in past from the day he started! Actually 370 and little, but does that change much..? He founds himself into completely different time. Time, into what humans count all mice as pests. Time, into what cats hunt and eat mice. Alner, the local mouse society leader, and hot-head Kurt were eyewitnessess to Topo's firework arrival. They told him about the many dangers, that lurks around. In middle of talk arrives group of cats - part of Topo's capsula had broke their party, and they arrive to investigate... Topo discovers, that this SantaCatalina wery much differs from the SantaCatalina, he remembers... Into look for home, Topo meets with the white mouse Mimi, and later with her owner Jean. They become friends. But by time ower all heads start form dark clouds. Missis Knopp wants remove the old rent-house, to free the place to build a new shopping center. Her cat Megalo discovers Topo as new threat...