Workmen are raising the walls around the Assemblies of God Church on the outskirts of Zanzibar's Stone Town. Sweating in the heat and humidity, they have cemented row after row of concrete blocks to a height of some 10 feet. In May this year a violent mob stormed this compound and burned the 500-seater church inside. Six months on from the attack tell-tale licks of black smoke still darken the cross on its repaired walls.
Bishop Dickson Kaganga, who now has bars on the window of his office, says he and his fellow Christians are "living in fear". The Pentecostal priest, whose car was also torched in the assault, talks darkly of a rising tide of radicalism on the Indian Ocean archipelago once famed for its cosmopolitanism and religious tolerance.
After 16 years work as a missionary on the overwhelmingly Muslim archipelago, the bishop has little doubt who is to blame for the attacks that ruined his church and ransacked several others. He points to the rise of a group calling itself The Awakening, or Uamsho in the islands' native Swahili. A religious charity which historically confined itself to propagating Islam but has recently entered the political realm with its own brand of faith-based populism. The group's loud calls for independence from Tanzania and anti-mainlander rhetoric have proven hugely popular. Mr Kaganga insists that they are "advocating chaos".
The church burnings coincided with the arrest of Uamsho's leader, the cleric Farid Hadi Ahmed, in connection with an illegal demonstration.
The following day witnessed some of the worst riots seen on Zanzibar.
The leadership of the group has denied any involvement in the attacks and no arrests have been made. Since then a pattern of arrests, riots and unrest has dogged the islands culminating the deaths of several protesters and one policeman earlier this month.
With its population of one million people split between the two main islands of Unguja and Pemba, Zanzibar is no stranger to political violence. Shortly after independence from Britain in 1963 the black African islanders, many of them descendants of slaves traded through the archipelago, overthrew the Arab Sultan of Zanzibar. A year later its new leaders declared union with mainland Tanganyika – creating Tanzania. The islands' history as an African entry point for Christian missionaries, a transit centre for the slave trade and a hub for Islamic scholars have all left their mark.
Little of this rich, turbulent history sits comfortably with Zanzibar's modern fame as a tropical tourist destination with a spiced history of cloves and slaves. Beyond the glamorously dilapidated streets of Stone Town and sun loungers of the beachfront hotels more than one-third of the population lives in grinding poverty. The large underclass, living in rural villages or the crumbling concrete apartment blocks built by Soviet-era allies in the 1960s, face problems which don't appear in holiday brochures.
Dadi Kombo Maalim, the chairperson of Zanzibar's youth forum says that unemployment among under-30s could be running as high as 80 per cent. Heroin addiction has been rising slowly since the 1980s and has now reached epidemic proportions. The popular scapegoat for all the islands' ills has been a half-century of union with the mainland, which is blamed for both the economic doldrums and the perceived creeping moral decay.
"Uamsho says that in the name of the union many corrupt things have been brought from the mainland," says Mr Maalim, who lists prostitution, drugs theft and alcohol. It has left many Zanzibaris feeling that Uamsho "speaks for them", he says.
Elections used to mean murderous clashes between the ruling CCM party and the opposition CUF – stern critics of the union. But two years ago this came to an end with a unity government, which succeeded in ending party clashes but left a political vacuum now being filled by an Islamic movement.
"It's easy to recruit people in Zanzibar because of poverty," says Hothman Masoud, Zanzibar's Attorney General. "There are elements of Islamic radicalism here but they previously found it difficult to get more substantial support."
The government was taken "kind of by surprise" the lawyer says by Uamsho's entry into politics. Nevertheless, he denounces the leadership of The Awakening as "opportunists" interested in advancing their own status and wealth rather than the principled clerics they are depicted by their supporters as being. Much of the political establishment on Zanzibar insist in private that wealthy outsiders from the Gulf states or Iran are suspected of backing Uamsho.
There are few obvious trappings of wealth at a meeting of Uamsho's leaders in a poorly-lit spice shop on the rougher side of the island's capital, Ng'ambo, which literally means the "other side" from touristy Stone Town. Bags of cloves sit alongside herbal cures for malaria and a DVD about the freemasons. A short-bearded young information secretary, Said Amour, laments 48 years of failure and says that "political parties have failed so we are now taking over".
Uamsho will not run candidates at elections but it will use "people power" to advance its agenda. That agenda includes a new code of conduct for the tourists who account for 80 per cent of foreign currency earnings. The group is open to foreign visitors but they must abide by local restrictions, he says, giving the example of Saudi Arabia, which has strict observance of standards of decency. He proposes a dress code, draconian limitations on the consumption of alcohol and private hotel beaches to prevent Western visitors corrupting locals. Uamsho is not seeking a theocracy on Zanzibar, he insists, and will stick to non-violent tactics. But the spokesman warns that "wabara" – mainlanders – will have to leave in large numbers as they are illegal immigrants.
There are increasing signs that an unnerved government which has quietly banned many news outlets from covering Uamsho's activities, is preparing for a crackdown.
But support for the enigmatic Uamsho shows no signs of waning.
In the mosques supportive imams preach in favour of the "freedom fighters" of al-Shabaab, Islamic militants up the coast in Somalia. Uamsho's critics are telling lies designed to destroy its reputation, warns Mr Amour, who says the people will not allow that to happen. "Give a dog a bad name and then kill it," he repeats several times.