Is Islamic State heading for Lebanon?
"The Islamic State has succeeded in awakening the monster within us," announced the Lebanese Broadcasting Corporation (LBCI) in its evening news bulletin on 8 September.
As the anchor read the news, the video of the beheading of a second Lebanese soldier was being posted online.
An IS statement released two days earlier said Abbas Medlej, a Shia soldier, had attempted to escape his captors.
After his execution, leaflets appeared in Shia areas of Lebanon's capital Beirut demanding that Syrian refugees leave.
Meanwhile, in the Bekaa Valley in eastern Lebanon, five Lebanese Sunnis were kidnapped in apparent retaliation for the killing.
The LBCI anchor's words described a descent into the "rituals of the civil war" as the kidnappings began and Syrian refugees were chased out of neighbourhoods by thugs with sticks.
Viewed from Lebanon, the expansion of IS in parts of Syria and Iraq over the past few months seemed to be a distant development.
But now, everyone seems to be asking the same question: Are they coming here? The possibility appears exaggerated at times, underestimated at others.
The IS militants who descended on the town of Arsal came from the mountains surrounding the village and straddling the border.
Chased out of the cities of the Qalamoun mountain range by Hezbollah and the Syrian regime, a number of opposition factions had set up camp in the mountains.
IS fighters were a minority among them; the al-Nusra Front, an al-Qaeda affiliate, is thought to be the biggest force in the mountains.
Furthermore, some of the fighters in the mountains had only pledged allegiance to IS days before the battle. It is unclear how solid their organisational and ideological ties to IS are.
In Syria and Iraq, IS has territorial depth to fall back on and to push forth from. In Qalamoun, they are a minority among larger groups which are themselves trapped and cut off from supplies.
Given this, scenarios of a looming invasion by IS fighters appear overblown unless and until they open a route from their strongholds in Syria to the Lebanese border.
But what if the group were to spring up from within?
A main demand of IS and al-Nusra, which has also captured Lebanese soldiers, is the release of Islamist prisoners from the Roumieh prison on the outskirts of Beirut.
The prison houses hundreds of inmates, including many who took part in battles against the Lebanese army in 2007. But dozens have been held for years without being tried.
In the predominantly Sunni city of Tripoli in northern Lebanon, many have been seething at the treatment of the Islamists in Roumieh.
"Fayez Karam gets two years, serves one and a half," a Salafi sheikh told me, referring to a Christian politician who'd been convicted of spying for Israel.
"Meanwhile an Islamist who simply received a call from a wanted man stays in prison for seven years without a verdict."
Many Sunnis also accuse the government of violating its official policy of neutrality on Syria's civil war.
While Hezbollah fighters have moved with ease across the border to fight alongside the regime, Sunnis suspected of militancy have faced the scrutiny of the state.
"It's that feeling that their blood is valuable and ours is cheap," he explained, "that could make more people support the Islamic State and the use of violence to deter injustice."
Lebanon has always been a country of extremes and opposites, but never more than now.
In streets lined with bars and pubs in central Beirut, destitute Syrian refugees brush shoulders with the rich and privileged.
With every new beheading, refugees face the possibility of being displaced once again from their street corners in Beirut, and their tents and shantytowns in the countryside.
Meanwhile, there are signs that Lebanon's political elites are gradually losing control over the masses.
One of the leaflets ordering Syrian refugees to leave a neighbourhood in Beirut warned Hezbollah not to intervene. Reports emerged that the Shia group was rushing to contain the anger on the streets after the beheading of Abbas Medlej.
For months, Hezbollah has struck a balance between drumming up support for its fight in Syria, and keeping its popular base under control. Now, they could be reaching the limits of their sway over their supporters.
Splits are also showing within the Sunni community.
In Saadnayel, the Sunni town in the Bekaa Valley from which one of the five men was kidnapped, there was a skirmish between supporters of Sunni leader Saad Hariri and opponents who tried to tear down his posters.
For years, the billionaire, backed by the West and Saudi Arabia, commanded majority support among Sunnis in Lebanon, and launched scathing attacks against Hezbollah, Iran and the Syrian government.
But he was constantly outmanoeuvred by his foes and forced into compromises for little in return.
The strains are also showing within the Islamist scene. The Salafi sheikh I spoke to in Tripoli has been receiving death threats from supporters of IS angered by sheikhs who are still reluctant to declare enmity to the Lebanese state and its institutions.
The first soldier to be beheaded was a Sunni, and the militants who beheaded both soldiers are thought to be Lebanese.
For IS, Sunnis who fight in national armies against them are reverts from Islam who have taken the side of infidels.
I asked the sheikh whether IS was recruiting in Tripoli.
"Not in public, no," he said. "But we don't know what goes on out of sight."