I’ve always assumed those massive 4.5-liter bottles of Johnnie Walker Red Label you see in the duty-free emporium at Ben-Gurion International Airport are there just for show. Who could ever imagine schlepping such a behemoth through the terminal and then stowing it away in the overhead locker? Two weeks ago, however, boarding a flight to Kiev for a conference, I counted three on the plane. And by the time we took off, they were all at least a third empty.

They were wielded by groups of men with shaved heads and large velvet black kippot making the annual pilgrimage for Rosh Hashanah to Uman, and the drinking began already in the smoking room in Terminal 3. They sat in circles, breaking open their cartons of duty-free Marlboros, one self-appointed rabbi would say a verse from the machzor (prayer book) or a quote from Rabbi Nachman, a l’chayim and the little plastic cups were emptied for another round.

Now, I come from a Hasidic family, learned to drink in synagogue and have a lot of sympathy for alcohol-lubricated yiddishkeit. But these gentlemen were not hasidim in any recognizable form. Their exuberant boozing wasn’t avodat hashem be’simcha – the service of God through joy – but an end in itself. I don’t want to impugn on all the approximately 30,000 who spent Rosh Hashanah at Uman, many of them undoubtedly were there in the belief that praying on his grave would help Rabbi Nachman of Bratslav, the controversial ascetic who died there 205 years ago, intercede on their behalf up on high. But many of the thousands who thronged Ben-Gurion and Kiev’s airport were so obviously there for the carnival, the drinking, the weed-smoking and the whoring. Because what happens in Uman stays in Uman.

Until the late 1970s, Bratslav was a little-known sect outside a few tiny enclaves in Jerusalem and Safed. Researchers of Hasidism and connoisseurs of Ashkenazi liturgy appreciated the way a few hundred families had preserved the old traditions, despite being decimated by both communism and Nazism. My father took me a few times to hear them sing in their Katamon synagogue, which was built after the previous one in Jerusalem’s Old City was razed in 1948 by the Jordanian army and local Palestinian rioters, just one of many Bratslaver shuls destroyed over the generations.

But it was only when the big wave of Jewish new-age spiritualism began in the 1980s that the Bratslav renaissance began. Some were truly attracted to Rabbi Nachman’s way of seeking God through solitude and simple, unadorned belief and joy, uncluttered by philosophy and theology. But many others just liked what they saw as an easy-going and undemanding life where all transgressions would be excused if they just went through the rites of chanting the gibberish of “the note” (and scrawling as graffiti), which the senile sage Yisrael Dov Odeser had fallen to him from the sky, in Rabbi Nachman’s handwriting. Reciting the Tikun Haklali, venerating one of Rabbi Nachman’s earthly representatives, they were insanely happy, whatever befell them in life, and made the pilgrimage to Uman.

Uman, an impoverished town in southern Ukraine, was anyway beyond the mountains of darkness for so many decades, as travel to and within the Soviet Union was restricted and any public show of Jewish worship forbidden. But the sudden popularity in Israel of Bratslav coincided with the disintegration of the Soviet empire and as the various sects grew, they had something new to offer adherents – a mystical jamboree on the blessed man’s grave.

Most of the original Bratslav community rejected these newcomers, sometimes ejecting them violently from their synagogues, but it didn’t matter as every split and schism just created new communities to join and holy men to follow. Bratslav went from being the “dead Hasidim,” those who had continued believing without a living rebbe, to a wild franchise in which anyone can own the brand.

There are, of course, many contradictions in Rabbi Nachman’s quotations (most of his writings were published after his death and were edited by his followers). One of the central ones is whether he actually meant his followers should make a pilgrimage to his grave if they were already in the Land of Israel. Many rabbis, including most of the leaders of the original Bratslavers, and scholars believe that his intention was to offer an alternative to the Jews in exile who had no hope of making it to the Promised Land in their lives.

Some rabbis in recent years have spoken out, largely unsuccessfully, against the pilgrimage which tears fathers and sons away from their homes and families on Rosh Hashanah, forces many of the penurious Hasidim into crushing debt – and then there’s what they get up to in Ukraine. Criminal gangs in both Ukraine and Israel have long been in control of many of the chartered flights and buses, and the sale of marijuana and prostitution around the grave.

The death of 28-year-old Amir Ohana, whose body was found three days after Rosh Hashanah in the lake near Rabbi Nachman’s grave, will almost certainly remain a mystery. Did he suffer an epileptic fit in the middle of a hitbodedut (solitary contemplation), fall in and drown, and if so, why wasn’t more attention being paid to his medical condition – or were there darker circumstances as the rumored signs of violence on his body may attest to? He left his wife and three small children for Rosh Hashanah. They won’t be seeing him again, just one more dark sign coming out of Bratslav that has been quickly swept away from the public eye.

Rabbi Eliezer Berland, leader of one of the largest and most powerful Bratslav sects, has been on the run for two years now, following charges he sexually molested wives of his followers. As a fugitive he’s escaped to Morocco, and then Zimbabwe, South Africa and Holland, where he was arrested, bailed and since absconded, perhaps to Guatemala. His followers have spent the last few years infiltrating, on his orders, Joseph’s Tomb in Nablus, evading both Israeli troops and Palestinian Authority security forces. In April 2011, one Bratslaver, Ben Yosef Livnat, was shot dead when he and his friends tried to drive through a Palestinian roadblock outside the tomb. Another bloody pilgrimage.

Less remarked upon cases of sexual abuse, neglected children and widespread truancy are accumulating around some Bratslav groups, but social services and police are notoriously reluctant to interfere in what is seen as internal community affairs. This has all the dangerous characteristics of a cult and should be the concern not only of Israeli authorities, but also of Jewish communities abroad, as many of those joining are immigrants, particularly from the United States and France. The pure and simple joy of the Bratslavers often seeing dancing at crossroads in Jerusalem and Tel Aviv has a darker side that we all should start waking up to.