It has all the ingredients of a novel: a secret informant, a spy agency and a computer disc reputed to contain incriminating banking data.
Liechtenstein is a well-known tax haven
The hero (or villain) is Germany's taxman who, armed with the disc, is going after the wealthy who use a neighbouring country to avoid taxes.
Germany's spy agency paid a reported 5m euros (£3.75m; $7.3m) for the data.
The probe has led to the arrest of the ex-Deutsche Post boss Klaus Zumwinkel, accused of evading 1m euros in tax.
Mr Zumwinkel, whose home and office were raided last week, is accused of using banks in nearby Liechtenstein to avoid paying tax. He resigned soon afterwards.
15 registered banks
Assets under management: $147bn
Currency: Swiss Franc
Official language: German
Area: 160 square km
Source: Liechtenstein government, bankers association
Prosecutors say that this is just one of hundreds of suspected tax evasion cases related to the alpine principality, famous as a discreet tax haven.
Chief prosecutor Christian Schmidt-Sommerfeld said that more raids connected with the investigation took place on Monday.
Germany's finance ministry confirmed that an anonymous informant was paid for the names of hundreds of account holders. It is not known which Liechtenstein-based bank or banks are involved in the inquiry.
LGT Group, a Lichtenstein-based wealth management firm, said on Friday that a former employee had stolen client data in 2002.
"There are indications that client data stolen from LGT has been unlawfully disclosed," the company said in a statement.
The company believed the matter closed, but recently became aware that the data had been "illegally" revealed.
Chancellor Angela Merkel will meet Liechtenstein's Prime Minister
Liechtenstein's Prime Minister Otmar Hasler will travel to Berlin on Wednesday to meet German Chancellor Angela Merkel for talks.
Chancellor Merkel made clear on Monday she will ask Mr Hasler for greater transparency from the principality in financial matters, saying the country's reputation in the financial world is at stake.
She acknowledged the steps Liechtenstein had taken in recent years to make its institutions more open. "That gives me hope that we can sort out what is outstanding," she said.
Tax evasion 'taboo'
Germany has been shocked by the arrest of Deutsche Post's Mr Zumwinkel, one of the country's most respected chief executives.
Michael Glos, Germany's economy minister, urged business leaders to become more ethical.
Bosses should "be aware of their function as a model for society", he said in a newspaper interview.
"Otherwise our social market economy will no longer be credible."
Deutsche Bank chief executive Josef Ackermann was also quoted as saying that "everyone in a leadership position should set an example, not just top managers".
"Tax evasion has to be taboo," he added.