[The silver mystery]

Outside Valleby's church, an extensive excavation is underway. For two weeks archaeologist Sofia Winge and her assistant Waldorf Eriksson have been digging feverishly to see if there is anything valuable hidden in the ground. On the last day they find lots of silver coins, probably from the Viking Age. Then, when signs of intruders are discovered, yet nothing appears to have been stolen, it is up to the team to figure out what is happening.