What really happened when the Arctic Sea cargo ship went missing amid allegations of hijacking and weapons smuggling? The BBC's Sarah Rainsford went to Kaliningrad to find out.
The man's voice on the crackly recording from onboard the Arctic Sea cargo ship sounds very calm, even cheerful.
"My last port of call is Jakobstadt, Finland."
"Your destination, sir? Bejaia?" the female coastguard asks from the station on the Dover cliffs overlooking the English channel.
"Yes, that's correct," the voice replies.
But the Arctic Sea never reached Algeria. This was the last recorded conversation with the vessel, two days before it disappeared amid rumours of a hijack, whispers of arms smuggling and the whiff of international conspiracy.
I was given the first copy of the call by Dover coastguards as I began probing the many theories about what happened.
The cargo ship was finally located by the Russian navy 300 miles (483km) west of Cape Verde.
Eight men said to have boarded close to Sweden were whisked away to a Moscow prison and charged with hijack.
After weeks searching the vessel, far out at sea, Russian investigators announced they had found no suspicious cargo.
But the official account leaves many questions unanswered.
How could pirates operate in heavily-monitored European waters? Would they really hijack a cargo of wood, or was something more valuable on board? And why did the alleged pirates surrender without a fight or a ransom?
Apart from fuel and provisions for the crew, [the Arctic Sea] was empty as a drum
The Russian Maritime Register in Kalingrad
Stitching together John le Carre-style plotlines is simple.
But pinning-down hard evidence is far tougher, and that seems deliberate.
The ship's crew is under a gagging order, and my requests for interviews with Russian investigators and officials have come to nothing.
Fuelled by a level of secrecy unusual even for Russia, speculation about the Arctic Sea abounds.
Most gripping is the theory prompted by an Israeli intelligence source who told the BBC that Israel had warned Russia it knew the ship was smuggling S300 anti-aircraft defence systems to Iran.
Israel feared those missiles would protect any nuclear weapons facilities Iran might be building. So the hijack was a cover story, the source said, to let Russia block the delivery and save face.
The Russian foreign minister denies there were S300s onboard the Arctic Sea, and Israeli sources will say no more. The story is implausible but not impossible - so I tested the practicalities.
Before its last voyage, the Arctic Sea spent almost three weeks in Kaliningrad for what its owner calls routine maintenance.
The Arctic Sea has a similar-sized hold to this one - did it contain missiles?
The militarised Russian region was a smugglers' paradise after the collapse of the USSR.
The Baltic Fleet there is equipped with S300 missiles. So Kaliningrad seems a prime spot to load secret cargo.
It was the first time the ship's owner had chosen the Russian port, but classification records I have seen show this was a scheduled docking.
"This was an intermediate survey. It was the end of year three in a five-year cycle so it fits," confirmed Vladimir Parshin, local head of the Russian Maritime Register.
"We have to check the tanks and the drainage system. We can't do that when the ship is loaded. Apart from fuel and provisions for the crew, she was empty as a drum."
But his team's last visit was on 16 July, and data from Lloyds Register/Fair Play indicates that the Arctic Sea remained in Kaliningrad another day.
Despite repeat requests, I was not permitted to visit Pregol shipyard to investigate whether an illicit cargo could have been loaded then.
Instead, I traced those who went onboard the Arctic Sea in Finland, where the ship took on its official cargo of pine. I discovered there was no physical inspection.
"If they say they are empty, they are empty," customs officer Kjell Lintholm told me. "We were on the ship for passport control, just documents. It was a normal ship."
But could a consignment of S300s have been hidden somewhere?
Inside the vast hold of a British-owned ship almost identical in size to the Arctic Sea, I watched dockers at work as cranes lowered mobile homes onto deck.
There is clearly ample space for the S300 launch vehicles, but no way for the Finns to miss them.
Moscow denies S-300 missiles were on board
The seven-metre long missiles are also hard to hide.
The only feasible place is the ballast tanks, so I squeezed through a manhole and climbed into one of them to take a look.
Access to all these dark, damp areas is through an oval hole about 80cm (31 inches) at its widest.
The space beneath is fairly generous but manoeuvring a long, thick missile in there would be impossible.
"You could squeeze something in, but not big stuff," the ship's Russian captain agreed. "And I don't believe these missiles are flexible."
Accessing the bottom ballast tanks would mean cutting open the lower deck and resealing it.
If the Russian navy was really scrambled to remove the missiles, it would have to do that from a fully-loaded timber carrier - out at sea.
Captain Yevgeny, like others I met, is deeply sceptical.
"If the tanks are covered, there is no chance to get in them," he told me.
Might a Russian naval frigate have transferred the timber?
"Everything's possible, if you really want it," the Captain laughed. "But it's closer to a fairy-tale. It would be a miracle."
Even allowing for that miracle, all this sidesteps other big questions including how the supposed missiles would reach Iran from Algeria, and why crossing the Caspian Sea was not simpler.
I have explored several alternative theories about the Arctic Sea, and interviewed dozens of people in many countries.
So far all versions are unproven and equally flawed.
Frustrating though it is, unless someone breaks their silence, what is left is a deep mystery and any thrilling plotline you care to choose.