When the Cavemice discover a giant oyster in the lagoon near Old Mouse City, they call on Geronimo Stiltonoot to help them fish it out of the water before the saber-toothed tigers find the pearl.
Geronimo Stilton. Micekings volume 6
One of the special helmets of Chief Sven the Shouter's private collection has been stolen. The mice journey to a rival village to find out.
Geronimo Stilton. Micekings volume 5
"The micekings have received a mysterious message in a bottle! Unfortunately, most of it has been damaged by water -- but Geronimo can tell it's from the Oofa Oofas, the laziest rodents in the ancient far north. The micekings set sail to Oofadale, in case the Oofa Oofas are in trouble. But on their way, the dragons attack! Fjords and fiddlesticks, what an adventure!"--