Footage of a wild lynx hunting a snowshoe hare.

Everyone knew this was going to be one of the series' most difficult shoots.

Up for the challenge was Canadian camerman Sam Ellis.

who went to the Yukon to see if he could film these elusive animals.

The plan was to search for lynx tracks and follow them to find the animals.

"These tracks here to the left, were here yesterday"

"and now we have all these other ones here."

But the lynx were incredibly elusive.

"We play this game of cat and mouse, I didn't get any footage today but"

"I was probably snowshoeing with three cats for about four hours."

So Sam tries another approach.

Here, some of the lynx have radio collars

and Sam got permission from the scientists to tune in.

While Sam knows where the lynx are, he still can't see them.

The bush is so thick, the lynx can keep out of sight if they want to.

"I think the most frustrating thing about these cats is they're so elusive, that even with the telemetry"

"even though we know they're right in front of us, we still can't find them sometimes."

"They're just that good at being hidden."

But there's one lynx that is beginning to make himself visible to Sam.

A male the researchers call "Mad Max".

Slowly, day by day, Mad Max is learning to trust Sam.

"He's comfortable enough you can see, he's actually going to sleep."

"He does not see us as a threat."

"It's amazing to be this close to a wild Canadian lynx"

"and knowing that we're not disrupting his natural behaviour."

Their unique relationship opens a window into the world of the lynx that no one has had before.

It's one thing to be close to Max when he's resting

but it's another to get close when he's hunting.

I've seen him chase two rabbits today

and uh, missed the opportunity twice.

But then, Mad Max suddenly realized that having Sam around,

could work to his advantage.

"Today, Mad Max, he became even more comfortable with me than he has before."

"We've always had to use the telemetry to find where he is and once when we find him he's okay with me being around"

"Today, he was making himself visible."

"Kind of coming up to me, saying like 'I'm here', and the walking in front of me, kind of luring me. "

"And I'm like okay. I always kinda had a feeling he might like having me around because I could be spooking rabbits."

"It kinda works to his benefit."

"Just a typical Sunday, talking my cat for a walk."

But it's still a struggle to get the camera in the right place at the right time.

And keeping up with the natural pace of a wild lynx is no easy feat.

Max glides easily across the snow

whereas Sam breaks through with every step.

After two months of grueling effort, Sam still has nothing.

As close as they've become, Sam is no match for Max in this snowy world.

And then one day, Sam finally gets a break.

"It was brilliant. I came down and I saw this rabbit in this wide-open meadow."

"The cat was stalking left, and I thought 'there's no way he doesn't see this rabbit in front of me'"

"So I set the camera down and started rolling on this rabbit."

"The cat did this big "J" stroke, all the way around into the meadow, and the rabbit was completely oblivious."

"They started coming right to the camera"

"He got within 3 feet before the rabbit even took off"

"and then they both came running, they ran right by the camera at a super high speed slow motion."

"I was just hoping not to shake the camera and not lose the focus. "

"I think it was... the best day of my life."

It took a special form of determination, and a remarkable relationship between cat and cameraman.

to finally claim this wildlife film first.