Bangkok is bracing itself.
Seven people have been shot and injured today, raising the spectre of more violence in the coming days as anywhere up to 100,000 protesters are expected to descend on the city, united in one aim: forcing out the government.
The authorities are planning to deploy more than 14,000 soldiers and police to try and maintain order. One foreign embassy has warned its expatriate citizens to stock up on two weeks supply of food, water and medicine. Fears simmer - as they so often do - of a military coup.
In the early hours of today, gunmen opened fire on anti-government protesters. The incident followed clashes between government supporters and protesters on Friday outside of Bangkok that left at least six people injured.
Thailand's army chief, Prayuth Chan-ocha, said he feared things were going to get worse. "I am concerned about security because there will be many people. The violence is increasing," he said, according to the Reuters news agency. "We can think differently but we cannot kill each other. Please don't use violence."
In the latest of a series of protests that have rocked Bangkok in recent months, sent the Baht tumbling and persuaded many tourists to go elsewhere, anti-government protesters plan to shut-down government offices, block major road intersections and even cut-off electricity supplies in an attempt to derail the authorities’ ability to govern.
Schools will be shut, though many shopping malls are expected to remain open. Protesters have vowed not to interfere with the operation of the airports, as previously happened, but nothing can be taken for granted.
The demonstrators are being led by Suthep Thaugsuban, a former deputy-prime minister who in October 2013 resigned from his position as a member of parliament and a senior figure within the opposition Democrat Party in order to lead the protests.
Mr Suthep and his supporters are seeking the ousting of Prime Minister Yingluck Shinawatra and her Pheu Thai-led government, which came to power after a convicting election win in 2011. They claim Ms Yingluck is nothing more than a front for her brother, Thaksin Shinawatra, a former premier who was ousted in a coup 2006 and who now lives in enforced exile in Dubai. They accuse him of widespread corruption and nepotism.
Late last year, the 64-year-old Mr Suthep, a former shrimp-farm and palm-oil tycoon, led a series of debilitating protests that shut down parts of Bangkok after Ms Yingluck and her government tried to pass an amnesty bill that would allowed her brother to return to Thailand.
Confronted by the scale of the protests and cautious of spilling blood on the streets, Ms Yingluck not only dropped the bill but announced she was terminating the government and set a new election for 2 February.
But the protesters have not backed down. Mr Suthep has called for an overhaul of Thai politics and said it must take place before any new election. The opposition Democrat Party, the country's oldest political party, has said it will boycott any election, raising more uncertainty.
Akanat Promphan, a spokesman for an anti-government group and another former Democrat party member of parliament who resigned to join the protests, said the movement had "gone beyond party politics". Speaking from Bangkok, he claimed "millions" of people would join the demonstrations on Monday.
"You have to understand this is nothing to do with any political party," said Mr Promphan, of a group named the People's Democratic Reform Committee (PDRC).
Asked why the group simply did not compete in the upcoming election, Mr Akanat said a series of reforms - of the electoral system, of the police service and of the constitution - were needed before a vote would have any meaning. "We are not doing away with elections all together. [But] we want reform before an election."
Yet the government of Ms Yingluck, along with many analysts, say that after a series of defeats at the ballot box, the opposition has essentially turned its back on electoral democracy. Rather, it wants to replace the elected government with an appointed "people's council".
"This a huge tragedy for the democratic system, not just for us but for all 50 parties that want to contest the election," said Sean Boonpracong, a national security adviser to the government, who said the country was facing a "possible abyss".
He added: "We have our backs against the wall. From our point of view, the election must go ahead to give us legitimacy."
The planned shutdown is the latest turmoil to have descended on Thailand since Mr Thaksin, a former telecommunications tycoon, was forced from power in a bloodless ought eight years ago. Scores of people have been killed, many of them in the spring of 2010.
The different forces lining up for and against the government led by his younger sister do not divide along entirely neat and precise lines.
However, Mr Thaksin has always had strong support among rural Thais in the north and east and the urban working class, who say a series of popular measures during his time in office raised their living standards and access to healthcare. Large numbers of working class people from Bangkok also voted for Ms Yingluck in 2011.
Ranged against that is a coalition of middle-class elements from Bangkok, business leaders, former military officers and the so-called "establishment" that surrounds the country's royal family. Mr Suthep has also been able to call on the support of considerable numbers of Thais from the south of the country, where he hails from but where Mr Thaksin's support is less solid.
One issue that could determine whether or not there is violence this week is whether supporters of Mr Thaksin, often collectively called the Red Shirts, also assemble in Bangkok in sizeable numbers.
Another uncertain factor is what role the military may yet play. The army has staged or attempted 18 coups in Thailand. This time it has remained publicly largely neutral, but Gen Prayuth has given some observers cause for concern by comments that have failed to rule out intervention.
"I cannot confirm whether there will or will not be a coup," he said last week.
Such is the concern about what may lie in store in the the coming days that on Friday, the UN Secretary-General Ban Ki-moon said he had spoken with both Ms Yingluck and the leader of the Democrat party, Abhisit Vejjajiva, in an attempt to broker a peaceful outcome.
"I am very concerned that the situation could escalate in the days ahead," he told reporters. "I urge all involved to show restraint, avoid provocative acts and settle their differences peacefully, through dialogue."