In the shaky video, a Saudi woman in an abaya and sunglasses is filmed from the front passenger seat of a car. She talks to the camera, eyes on the road, as palm trees on the streets of the eastern Saudi city of Khobar slip by. Within hours, she was detained for an act that is not a criminal offence.
As many people now know, the woman in the car was Manal Al Sharif, a security consultant who has been using social media to highlight her campaign to change social norms in Saudi Arabia and allow women to drive in the kingdom. Ms Al Sharif was later released, but not before sparking copycat videos in Saudi Arabia and media coverage around the world.
On the surface, Ms Al Sharif's demand seems simple with arguments in its favour.
Foreigners tend to imagine that citizens of wealthy Saudi Arabia have attendants to carry out even the most menial tasks. Yet for many families and women, the cost of a driver is significant and some struggle to find the money. Moreover, women become dependent on their drivers, with even professionals reduced to a standstill if they cannot find someone to drive them.
Yet the driving "ban" is merely one aspect of a larger social and political edifice, a debate that goes to the heart of the kingdom and a demand with far-reaching consequences.
To understand why, it is important to recognise that Saudi Arabia is remarkable compared to other nation states in that the political authority of its leaders rests to a large extent on their role as defenders of the Islamic faith.
King Abdullah is first and foremost the custodian of Islam's two holiest places, a responsibility that supersedes his role as head of a nation state. In that capacity, the king wields both spiritual authority and temporal power.
Aside from the role as custodian of Islam's holiest sites, there is also a long-standing religious-political union. Since the 18th century and the rise of the Saud family, politics has been linked with the ideas of what is called the Wahhabi movement. An austere interpretation of Islam, "Wahhabism" flourished among the clans of this part of the Arabia Peninsula for at least two centuries. The religious ideas of the eponymous Mohammed bin Wahhab and the political rise of the Saud family have been mutually reinforcing.
This is a complex history of only one part of the Arabian Peninsula, but because of oil revenues, geographical location and the holy sites, these events have taken place in view of much of the world.
Inside the kingdom, there is an open political contest among several competing ideas. The austere Salafist ideas of Wahhab, which also have political power because of influence in the religious and educational establishments, compete with a rising tide of Islamism, similar to that seen elsewhere in the Arab world, most strongly represented in the kingdom by a movement called Al Sahwa Al Islamiya (the Islamic Awakening), as well as a socially liberal movement that focuses less on religion than on rights. The leadership tries to draw a balance among these groups, but now, as the Arab world is changed by revolutions, the stakes are rising. At the exact same time and for the exact same reason, the newer movements feel empowered to push for change.
All of which brings us back to that woman in the car in Khobar.
The driving ban isn't really a ban - there is no law against women driving in the kingdom. Rather, it is a religious edict that is now part of the social custom of the country. This custom fits into the broader edifice of the "guardianship" system that runs through Saudi society. It has gained some legal legitimacy, because the state will not issue driving licences to women.
The Saudi guardianship system is complicated but means, in practice, that women have to obtain permission from a male guardian - from their father or husband, or even from their son - to be able to work, to travel, to approve their choice of marriage partner. More than any single law, this system denies women the basic capacity to conduct their lives in a way that women in neighbouring countries consider unremarkable.
Reformists in the kingdom worry that the issue of women driving will eclipse these other, larger, issues. Yet it is precisely because the driving issue goes to the heart of this political-religious edifice that the ban arouses such passions within Saudi Arabia. When it comes, women driving may herald other changes - and it is precisely because of this that activists Ms Al Sharif are pushing so hard and the conservatives are pushing back.
Thus what seems like a small, not even illegal, act in reality has much bigger consequences. The alliance of the ruling family with a religious movement, and the Saudi guardianship of Islam's holiest sites, mean that change is glacial, the reform of an entire way of thinking rather than just one decree from above.
It is inevitable that Saudi women will gain the right to drive. It is noticeable that in countries such as the UAE and Yemen, which share similar customs and values, women drive with no corresponding social problems. The Saudi exception may not be long lived.