Tonight:

A hard hack to follow. There's new evidence that Chinese hackers had their way with Nortel's computer network -- and that Canadian officials didn't do their part to fight back.

Belittled knowledge is a dangerous thing. Why American scientists are speaking out for their muzzled Canadian colleagues.

Fire trap. In Honduras, a prison goes up in flames -- killing at least three hundred prisoners.

Sifting through the shifts. How the changes in Middle Eastern politics and diplomacy are changing Hamas.

One good vacuum deserves another. The details on a Swiss plan to clean up the junk floating around above the Earth.

And...speak of the daredevil. Not long ago, Canadian authorities told Nik Wallenda he absolutely could not tightrope-walk across Niagara Falls -- and now they've told him he definitely can.

As It Happens, the Wednesday Edition. Radio that puts the "fun" in "funambulism".

For some employees at Nortel, it must have been a frightening sight: computer screens showing large batches of confidential data, being extracted from servers in Ottawa, and downloaded to unknown computers in China. It's now thought to be a classic case of corporate espionage in a wired world. And, according to one former employee, it lasted for nearly a decade.

This week, the Wall Street Journal broke a story about Chinese hackers who spied on and gained control over Nortel's computer network. At the time, Brian Shields was a Systems Security Senior Advisor there. He worked for the now-defunct telecommunications giant for over eighteen years. It was his job to find out who was behind the attack. And when he did, Mr. Shields says Canadian authorities dropped the ball.

We reached Brian Shields in Raleigh, North Carolina.

They were trapped in their cells as the fire raged. And in the end, more than three hundred inmates of a Honduran prison died.

Others survived and are in custody. Some may have escaped.

It is the deadliest prison fire in the country's history. As we go to air, there is still some uncertainty about how many of the eight hundred inmates at the facility in Comayagua survived -- and who they are.

Hernan Lopez is following the fire from the capital of Honduras, Tegucigalpa. He knows a prisoner who was in the Comayagua jail last night when it caught fire -- a man whom Mr. Lopez helped to raise.

It's been something of a balancing act.

Nik Wallenda is an American highwire walker. And for a very long time, he's wanted to walk across Niagara Falls. Now, officials on the American side of the falls never had an objection. But officials on the Canadian side had many.

Until today, when the Niagara Parks Commission overturned its decision and decided to OK Mr. Wallenda's request.

Mr. Wallenda is planning the stunt for sometime this summer. In the meantime, he's just really excited. For the record, here is Nik Wallenda speaking to CBC News Network's Carole MacNeil earlier today.

For the record, that was Nik Wallenda speaking to CBC News Network earlier today.

Janice Thompson is the Chair of the Niagara Parks Commission. We reached her in Niagara Falls, Ontario.

"The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom."

At least, that was Isaac Asimov's take on the gulf between science and society. And it follows that trying to make sure the public knows what researchers are up to is pretty important. But for Canadian government scientists, it's becoming more and more difficult to span that gulf.

Which has the American Association for the Advancement of Science concerned. Later this week, as the AAAS meets in Vancouver for its annual conference. It's the largest scientific gathering in the world. And on Friday, it's holding a session called "Unmuzzling Government Scientists."

Francesca Grifo is the Director of the Union of Concerned Scientists' Scientific Integrity Program -- that's a non-profit association that works to keep scientific research free from government interference. She'll be speaking at the session on Friday. We reached Dr. Grifo in Washington DC.

She has been showered with honours, and acknowledged internationally as a master of the short story. Nationally, though -- that is to say, in her home country of Canada -- Mavis Gallant is not exactly a household name.

The eighty-nine-year-old writer still lives in the same small Parisian apartment she moved into nearly fifty years ago.

Tonight, on "Ideas" on CBC Radio One, journalist Megan Williams paints a portrait of Ms. Gallant, in her documentary, "The Four Seasons of Mavis Gallant". Here's an excerpt from the program, in which Mavis Gallant talks about her first year in Paris, at a time many Canadian writers were passing through -- including Morley Callaghan, poet John Glasscoe and -- as she recalls in this clip -- Mordecai Richler.

Whether it wants to or not, the Palestinian organization Hamas is changing.

Its old alliances are weakened. And as the Arab Spring begins its second year, new influences are tugging at the old power structures of the Middle East.

In the past week, the rival leaderships of Fatah and Hamas have announced a unity deal. The old headquarters-in-exile of Hamas in Syria has been emptied. And the once-isolated, Iran-backed leadership of Hamas has been on a whirlwind tour through the wealthiest pockets of the Middle East, visiting countries that a year ago shunned the organization.

Ahmed Yousef is a senior official in Hamas, and an advisor to Gaza Prime Minister Ismail Haniya. We reached him in Gaza City.

And now, it's time for an audio Choose Your Own Adventure. Please, play along at home.

Page One: You're a journalist, and you come across a story that combines Jamie Oliver, one-point-five million dollars in jewellery, a collection of guns, and rare master tapes of the bands Joy Division and New Order. If you choose to cover it, turn to Page Twelve. If you choose not to cover it, turn to Page One-Hundred-And-Eight.

Page Twelve: You have learned a little more about the story. It concerns the adorable British chef who goes from door-to-door threatening people until they throw out their junk food. He's turning an old building into a restaurant. The old building used to be a bank. And when the bank left, it emptied all the safety deposit boxes that hadn't already been emptied.

That's when the one-point-five million dollars in jewellery, the collection of guns, and the rare master tapes of the bands Joy Division and New Order were discovered. If you choose to cover the story, turn to Page Fourteen. If you choose not to, turn to page One-Hundred-And-Eight.

Page Fourteen: You have learned even more about the story. You have learned, essentially, that it's a non-story, and there's no reason to cover it. It turns out that the contents of the safety deposit boxes -- the jewellery, guns, and master tapes, and everything else -- were actually discovered 'way back in 2008, when the boxes were emptied out. Also, the article you read repeatedly uses the word "allegedly". Also -- most damning of all -- you found it on the Daily Mail website. If you still choose to cover the story, turn to Page Sixty-Seven. If not, turn to page One-Hundred-and-Eight.

Page One-Hundred-and-Eight: With a heavy sigh, you compromise. You won't cover the story, but you will play some old Joy Division, and hope no one really notices there's no legitimate reason to do so.

Thirty years ago today, the Ocean Ranger oil rig was hit by a heavy Atlantic storm. Just after midnight, a mayday call went out -- the rig was listing, and those on board needed immediate assistance.

Poor weather prevented that assistance from arriving until it was too late. The Ocean Ranger sank on the Grand Banks east of Newfoundland. All eighty-four people on board died.

Five of the victims had graduated from Gonzaga High School in St. John's. Every year the school holds a public memorial.

For the record, this is student Katherine Brown, from today's memorial in St. John's.

For the record, that was Gonzaga High School student Katherine Brown, at a service today in St. John's Newfoundland, commemorating the thirtieth anniversary of the sinking of the Ocean Ranger.

A commission looked into the cause of the disaster. After two years, it concluded that design and construction flaws -- as well as inadequate safety training and equipment -- were largely to blame for the tragedy.

That's what Rob St. Aubin was saying right from the start. He worked on the Ocean Ranger, and had left the rig just days before it went down.

From our archives, this is an interview from February 15th, 1982, the day the Ocean Ranger sank. This is Rob St. Aubin speaking with "As It Happens" host, Elizabeth Gray.

In Russia, it's OK to criticize the Kremlin -- so long as there aren't too many people listening.

The radio station Ekho Moskvy -- or "Echo of Moscow" -- has long been an outlet for independent voices in Russia. Voices willing to take on Vladimir Putin. And its audience has been relatively small.

But now that Russians have begun protesting against political corruption, it seems Mr. Putin may be concerned that the station is becoming more powerful. Just weeks ago, the Russian prime minister publicly criticized the radio station. And, yesterday, its editor, Aleksei Venediktov, stepped down from its board of directors.

Dmitry Babich is a Russian journalist and political commentator. We reached him in Moscow for his take.

The RCMP investigator who wrapped up Canada's largest serial killer investigation says it was a monumentally difficult task. Don Adams was brought in to oversee the investigation which led to Robert Pickton being charged with the murders of twenty-six women.

The retired RCMP Staff-Sargeant is testifying at the missing women inquiry in Vancouver, which is examining the shortcomings of the investigation. Today, Don Adams told the inquiry that, in retrospect, it may appear that Robert Pickton was the most obvious suspect. But when the suspects actually numbered in the hundreds, the investigation became quite complex. Here is part of what Don Adams had to say today, for the record.

There is shock at a Texas university. The head coach and star players of the championship team have left. They're relocating to St. Louis. And chess fans are devastated.

Because I'm talking about the chess team.

Former women's World Chess Champion, Susan Polgar, started the Susan Polgar Institute for Chess Excellence -- or "SPICE" for short -- at Texas Tech. And she took the University to the top of the college chess world.

But now she is making a daring gambit -- moving to Webster University in St. Louis. And what's more, she's taking her top chess champs with her.

We reached chess Grandmaster Susan Polgar in Lubbock, Texas.

Contrary to its name, space is pretty crowded. At least the patch of space directly above the Earth. Years of human exploration has left a lot of junk up there -- discarded bits of technology; abandoned satellites; rocket parts; chunks of flotsam and jetsam that are orbiting at high speeds.

So now there`s a new space race, this time to develop something that will clean up the mess.

The Swiss Space Centre has announced that it is developing something called CLEANSPACE One. It's a project to develop and build a family of satellites specifically designed to clean up space debris.

Volker Gass is the director of the Swiss Space Centre at École Polytechnique Fédérale de Lausanne. He's in Lausanne, Switzerland.