Who stole the Viking's treasure?

Helge Helgeson, the old jarl of Haithabu is dead! In keeping with ancient Viking traditions, he is to be buried at sea. But the night before the ceremony is due to take place the ship disappears! And with it the treasure that is meant to accompany the dead ...

Rome at the time of Caesar: when the four children Cornelia, Titus, Gaius and Publius dig up an old amphora they find in the mud of the Tiber, they are quite sure it must be hidden pirates' treasure. But the amphora contains neither gold nor precious stones, instead there's a ...