As I flew in to Guantanamo Bay on a small commercial plane recently, I squinted out of the window. A grey aircraft crouched at the end of the runway. Given the Bush administration's maverick rendition policy, I wondered whether the plane had been used for one of those forcible, extralegal transfers of prisoners to a torture chamber.
I had intended to visit a prisoner from Tunisia called Abdullah Bin Omar. The administration once pretended that Bin Omar was among the worst of the worst terrorists on earth. More recently, a military tribunal cleared him for release, finding that he was no threat to anyone. To be sure, such Guantanamo tribunals are themselves a travesty, relying on coerced and secret evidence, but at least Bin Omar was allowed to be present to argue his innocence.
I had planned to advise Bin Omar on his right to asylum. Tunisia has a far longer pedigree than Guantanamo's when it comes to denial of due process. Two colleagues recently travelled to Tunisia on his behalf and found that he had been sentenced in absentia to 23 years in prison. It was clear that he would be better off serving his sentence in absentia. He was almost certain to face torture on his return.
All of this we had communicated to the US government - only Bin Omar did not know the full extent of his peril in Tunisia.
I never got to see my client. The day after I arrived, as evening drew in, that grey plane took off. Having stalled me for a week, the US government then sent us an email saying that Bin Omar had been a passenger on it.
President Bush is becoming increasingly desperate to close Guantanamo. The Caribbean prison has always been a nightmare for its prisoners; it has now become one for the captors, too, who are finally beginning to recognise what creating "the legal equivalent of outer space" has done for the international reputation of the United States.
George Bush has said that there are obstacles to closing the prison. He is right. Unfortunately, Bin Omar was such an impediment. The US originally bought him for a bounty in Pakistan, where he had been minding his own business, safe from Tunisian persecution. The US military had rendered him halfway around the world to Cuba, but now they wanted to get rid of the human detritus left in Guantanamo Bay.
The state department has piously insisted that the US will not release prisoners to places where they face persecution. Yet Bin Omar was taken to Tunisia. This was the same state department that issued its annual report just three months ago finding that the Tunisian "government [had] continued to commit serious human rights abuses" and had "tortured and physically abused prisoners and detainees", likewise noting that "lengthy pretrial and incommunicado detention remained a serious problem".
So Bin Omar was once again rendered against his will to face detention and abuse. Nor will Tunisia allow us to see our client, but he has been able to get word out about his reception by the Tunisian authorities. He has already been tortured, and he has been told that if he does not confess falsely to crimes, his wife and daughters will be raped. There is doubtless worse to come.
There are many other Guantanamo prisoners facing Bin Omar's fate - from Tunisia and from Algeria, China, Egypt, Jordan, Libya, Syria and Uzbekistan. Like him, many have been cleared for release. Much as they want to get out of Guantanamo - a purgatory of imprisonment without charge or trial - repatriation may take these men to hell itself.
But President Bush wants to get rid of this embarrassment. Clint Williamson, styled as the "US ambassador-at-large for war crimes issues", recently completed a whistle-stop tour around North Africa, meeting with local officials to discuss repatriation "options".
There is no court where I can plead Bin Omar's case now, save for the court of public opinion. The Bush administration wants the American judges to dismiss his case as "moot", because he is no longer in their jurisdiction. Yet a crime has been committed here: a human being has been sent to the torture chamber.
The British government's recent predilection for sending asylum-seekers back to North Africa is little better. If Gordon Brown and David Miliband are to reinvigorate the 1997 promise of an ethical foreign policy, they must stand up for those who face torture.
More prisoners will be leaving Guantanamo for their home countries in the weeks to come. The closure of that appalling gulag may be trumpeted as a triumph of human rights, but the husks of the prisoners who have suffered so long are merely being passed down the line for the next chapter of their abuse.
Clive Stafford Smith is legal director of Reprieve, a UK charity that provides front-line investigation and legal representation to prisoners denied justice by powerful governments across the world. His book "Bad Men: Guantanamo Bay and the Secret Prisons", has just been published by Weidenfeld & Nicolson. He writes this column monthly. Contact Reprieve at email@example.com  or at PO Box 52742, London EC4P 4WS (tel: 020 7353 4640)