Flanked by a heavily armed private security team, David Shearer is trudging around the labyrinth of makeshift huts at the Protection of Civilian Site 3. Guarded by the United Nations, the camp is home to more than 31,000 people displaced by war.
One of his staff eagerly informs his boss that the defensive tower they're about to inspect is "very robust". Once inside, Shearer, who leads the UN mission in South Sudan, is shown three machine guns that have recently been installed against the mud-packed barricades at the UN camp in Juba.
White tanks with the signature black UN stamp sit idle against the razorwire perimeter of the site. From the tower, Shearer can look out across the sea of white tents. After being subjected to a campaign of killings, rape and fear, the defenceless have sought shelter here.
It's a world away from his home in leafy Point Chevalier, but Shearer, the former Labour leader who stepped down as MP for Mt Albert in December, looks like a man in charge. Wearing army-green chinos and a light blue shirt, he shakes hands and engages in small talk with some of the UN troops in his laid-back Kiwi way. He smiles and listens. But underneath the pleasantries, he knows the situation here is dire. Having worked in places such as Iraq, Afghanistan and Kosovo in the past, he's no stranger to the world's most hostile conflicts. But Shearer says the task he's faced with in South Sudan is one of the most challenging he has encountered.
Shearer is in charge of around 14,000 peacekeeping troops and police officers. Just deploying troops and getting supplies into most areas is a logistical nightmare. The roads are often impassable, there are military checkpoints everywhere, and fighting can make any form of travel too dangerous.
And then there is the sense of isolation. "It's sort of lonely in a way, but that's just part and parcel of the job, particularly if you're the leader an organisation like this. As they say, it's lonely being at the top."
It may be lonely in part because of the grinding demands of daily life, his 7pm curfew, and the seemingly impossible task of facilitating peace in a land where war is entrenched. He's also a long way from his wife and children. He returned home recently, but such trips don't happen regularly and he largely relies on Skype to catch up on life back in New Zealand.
South Sudan's bloody four-year-old civil war has produced the world's fastest growing refugee crisis. More than 1.5 million have fled to neighbouring countries and a further 1.6 million are internally displaced. Shearer's job is to not only protect civilians and oversee the investigation of human rights abuses, but to also try to guide the country's leaders on a pathway to peace. That aspect of the job, he says, is "hugely challenging".
Multiple promises of ceasefires and peace agreements have failed. Shearer says the violence has only worsened in recent weeks. "There's now fighting on four different fronts across the country and outbreaks of sporadic violence in other places."
Shearer is adamant peace will only be achieved through a concerted effort from both sides to work together. "It's about trying to bring about a political settlement, not a military or violent one".
But that's incredibly hard when you're dealing with two political opponents who are both ex-soldiers. After years of war, the country is awash with weapons. Negotiations here usually happen through the barrel of a gun. It feels a bit like the world's superpowers have given up on the basket case that is South Sudan. The guns and ammunition fuelling the misery come from Eastern Europe and parts of the Middle East, including Israel. Despite warnings of genocide, a draft resolution to impose an arms embargo on the world's youngest nation failed last year after Russia, China and three African Council members, Angola, Egypt and Senegal, rejected the plan.
Shearer has inherited the role as head of mission for the UN here at a time when confidence in the organisation has been severely shaken. In July last year in the capital Juba, a bloody three-day battle broke out between factions loyal to President Salva Kiir and those who support his former deputy Riek Machar. Both men had been in town for peace talks.
More than 300 people were killed and an investigation into the response by the UN was labelled "chaotic and ineffective". Multiple calls for help went unanswered, and on at least one occasion a woman was sexually assaulted in front of UN troops who ignored her screams and remained at their post. Staff from the World Food Programme requested protection at its compound, but no help arrived. When the fighting stopped, $41 million worth of food and equipment had been looted.
Shearer accepts the UN response during this time was lacking. The peacekeepers are from 45 different nations and most are there on short term contracts. They don't arrive in South Sudan wanting to fire their guns and kill. Despite an obvious reluctance to get involved in fighting, Shearer does want to change the perception that the UN isn't willing to step up. "I've insisted that our peacekeeping force be more robust over the last few months. We've had standoffs where weapons have been cocked and we've stood our ground."
He points to a recent attack on a UN base in Leer where the Ghanaian contingent fired back, protected the base, and successfully repelled the onslaught. "I was really proud of them and I told them that and I think they set the bar for the way I expect our peacekeepers to respond ."
In another case, Mongolian troops stopped fighters from abducting a group of young boys to be used as child soldiers.
The constant threat of violence has wider repercussions.
Unity State in the north of South Sudan is in the grip of famine " the first famine announced in the world for six years.
Shearer says it's a man-made disaster. Thousands have abandoned their crops, their homes and, in many cases, their families. Fighting has cut off food supply routes, closed borders and put enormous pressure on humanitarian organisations.
At an emergency feeding site in Northern Bahr el Ghazal, the children arrive for screening frail and frightened. Dozens are weighed and measured as health workers document the disaster in dust-filled scrapbooks. Plenty of hunger related deaths have already been recorded in this region, which is on the brink of being officially declared in famine.
The women arriving at the site look exhausted and desperate. Some have walked hours.
Cradling her daughter, mother Aweng Piol says: "I don't know whether it is disease or hunger, but my child keeps losing weight. I have nothing to give her and I'm really worried she might die."
Another woman, Bakhita Avuk, says her 2-year-old hasn't eaten since the previous morning. It was a meal of cooked leaves.
Her eyes harden as she says she recently buried another of her children.
The 300-odd children screened during our visit get a special high-nutrient powder. But as it's the only food families have, it often ends up being shared among many.
Even during monthly ration distributions, the need is overwhelming. Hundreds are registered to receive food including rye, sorghum and oil from World Vision through an innovative programme that requires beneficiaries to plant crops.
But alongside those getting supplies are hundreds of people who are unregistered. They wait and hope they'll get help too, but most leave empty handed.
Little boys snap up beans that spill from aid sacks onto the dusty red earth.
Across East Africa, almost 23 million are severely food insecure. Hundreds of people - mainly those fleeing war in South Sudan - arrive at Kakuma Refugee Camp in northern Kenya every week.
At the arrivals area I was approached by a man from Burundi who told me how he'd been tortured by the military there.
At a food distribution site within the camp, mother Ajulu O'Koce detailed how she'd been raped by soldiers in 2008 while trying to escape war in her homeland of Ethiopia. When her brother tried to find her attackers, he was shot. She's been here for 10 years and will never return to Ethiopia. She has no expectation that she'll ever leave Kakuma. She says she at least she feels safe.
The numbers pouring into places like Kenya has put huge pressure on a region that's struggling with a shortage of resources and in the grip of the worst drought in more than half a century. Farmers talk of entire herds of animals dropping dead in the heat. The dry conditions are not only causing starvation and loss of livelihoods; it means farmers can't trade animals to pay their children's school fees.
But despite the hardship, there is resilience and a determination to carry on. Children smile and joke. They watch captivated by the sight of two tall white men sweating and lugging around piles of camera gear. A group of children push an old tyre around, and play a game of swing ball with an old plastic bottle. There are shrieks of laughter and there is still hope in this place of disaster and destitution.