Across France, scores - possibly hundreds - of towns and cities are hoping Switzerland will rescue them from a debtor's hell.
During the boom years of the past decade, the A-list resort of St Tropez, the industrial city of St Etienne, the glum Paris suburb of Argenteuil and many other towns signed up for complex long-term loans linked to the Swiss franc. Today, those borrowings have become a time bomb.
Under these deals, the council would sign up for a loan over, say, 10 to 20 years, in which the first few years would have very low interest rates, sometimes just 2 or 3 per cent annually.
Thereafter, the interest rose a couple of points but also became variable, fluctuating according to the exchange rate between the euro and the Swiss franc. If the Swiss currency went above a set ceiling, interest rates would go up. If it kept rising, the rates multiplied several fold - and in some contracts, there was no limit to the increase.
To council treasurers used to simple arithmetic and a cosy financial environment, these "structured rate" loans must have seemed a terrific wheeze. The deals offered a tempting opportunity to save money on borrowing compared with fixed-rate conventional loans.
And, or so it seemed, there was very little risk as there was little fluctuation between the two currencies.
Alas, the storm clouds started to gather after the 2008 financial crisis, and have been turning darker and more threatening ever since. Since 2009, the Swiss franc has risen in value by about a fifth, driven in part by debt crisis in the 17 eurozone nations as investors sought a safe haven.
As a result, France's municipal borrowers are now facing interest rates that in some cases are already painful and are likely to become excruciating.
The repercussions locally are already being felt as councillors point the finger at each other, but the effects could ripple across France's banking sector if towns become insolvent.
In the case of St Tropez, annual interest charges on its three "Helvetix" Swiss franc loans could rise from 3.94 per cent to 30 per cent from next year, sending the bank debt to €48 million ($81 million) for a council that has annual income of €45 million.
Argenteuil faces interest repayments of €33 million on original borrowings of €40 million. Unlike St Tropez, which says it has renegotiated four other Helvetix loans, the council says it is tied to punitive clauses if it wants to repay the debt ahead of schedule.
"It would cost us €93 million to pay it back, if the cost of getting a conventional loan to help with the repayment is factored in," said Joel Fournier, in charge of financial services at Argenteuil. "We just can't afford it."
How many other councils have become mired in such loans is unclear.
The daily newspaper Le Parisien says hundreds had been trapped, but the head of the Association of the Mayors of France, Jacques Pelissard, said he had heard of only "about a dozen" councils of various sizes that have the problem.
Some, such as St Etienne and the centre-western town of Angouleme, are lobbying the Government to take over toxic debts. But the Finance Ministry - which has enough headaches of its own - is standing firm.
Several towns are filing suit, or threatening to do so, against the banks that sold them the loans, claiming they were misled about the risk.
Claude Bartolone, head of the county council in Paris' Seine-St-Denis, has set up a website on which local authorities can share their experiences about toxic loans and seek help. "People are phoning every day to join up," he said.
Eyes are now riveted on what happens in Switzerland, because the Swiss central bank has declared war on the franc's rise, naming it a threat to Swiss exporters and the tourism industry.
On Tuesday, it stunned currency markets by announcing it was prepared to buy foreign currencies in unlimited quantities to limit the parity to 1.2 Swiss francs per euro.
On the first day, the exchange rate plunged 8.5 per cent, settling near the 1.2-franc target.
But analysts warn that the goal will be hard to defend in the financial psychosis that has gripped Europe today.
An analysis by the Swiss bank Julius Baer says the central bank may have to spend as much as 100 billion francs a day, on the basis of the worst turbulence in the currency markets in recent months.
That is the equivalent, in a week, of the country's entire gross domestic product.