Oh, what a year!

There were plenty of doubters when CBS announced it was moving "Hawaii Five-0" from a highly competitive time slot on Mondays to Friday nights, which some critics called a graveyard for television.

But "Five-0" executive producer Peter Lenkov never stopped believing in his show’s power to draw fans.

"I think the press started talking about shows going to the Friday night scrap heap," he said. "For me that was never the case. But every time you make a move, you hope your audience follows you."

And it did — or at least enough of it.

"Five-0" finished its fourth season Friday by winning the hour with 9.21 million viewers, capping an unblemished run of ratings wins that started with the season four premiere Sept. 27.

According to Nielsen ratings released by CBS, the show averaged 9.71 million viewers, which is lower than the average for season one (11.24 million) and season two (10.66 million), but higher than the season three average of 9.02 million.

Despite his optimism, Lenkov still considers the success of "being able to survive on Friday night" one of the high points of the season.

"We are doing better than most shows do on any other given night," Lenkov said.

The steady ratings, along with the well-received casting additions of Chi Mc­Bride and Jorge Garcia, are what Lenkov called three proud moments of the season.

Topping that was the season’s tenth episode, "Ho‘o­nani Makua­kane," which is Hawaiian for "Honor Thy Father." The Dec. 13 episode explored the shameful World War II internment of more than 2,000 of Hawaii’s Japa­nese citizens.

Even as the plot held true to "Five-0" constants — murder, crime, an investigation — it also featured flashback scenes of an internment camp built in Kunia during the war. The show built a replica of the camp for the episode using real blueprints and filled it with actors dressed in historically accurate military uniforms and internees who mirrored photographs taken of the real camp.

For many viewers it offered a chicken-skin moment rarely seen on network television.

"That wasn’t one we could do on any other show," Lenkov said. "You have to be down the road in a series in order to do something special like that. I think we earned the audience’s respect if you can do something outside the box like that."

The fourth season also saw the departure of series regular Michelle Borth, whose character, Catherine Rollins, was the longtime girlfriend of "Five-0" leader Steve McGarrett. Lenkov said the farewell exchange between Rollins and McGarrett, played by Alex O’Loughlin, was the season’s most memorable scene.

"I think the moment McGarrett says goodbye to Catherine and finally says ‘I love you’ — you could see the sadness and the pain on his face," Lenkov said. "And you really felt for Catherine. It was well acted all around. It really stands out as a really special moment."

Fans speculated for weeks that Borth’s departure was due to friction they said the actress created on social media outlets, especially Twitter. Lenkov said that was not the case. Her departure was the end of a two-year contract Borth agreed to when Lenkov made her a regular starting in the third season, he said. Her promotion from occasional episodes came with an expiration date and a character arc that his writers adhered to, he said.

"I’d love for her to come back," Lenkov said. "That is the plan, one day, for her to come back."

The "Five-0" cast and crew have been on hiatus since March 21 and will return to the set July 7. Their fifth season will promise a lot of plot developments, Lenkov said, but nothing will top what happens when they start shooting the seventh episode in September.

That will be the show’s 100th episode, traditionally a milestone for any series.

"Those are always special," he said. "I am looking forward to writing that one."

As for whether fans can expect another Sunset on the Beach premiere in Waikiki in September, Lenkov said he already is talking to CBS about making it happen.

"I love the fact that there is a real audience there on the beach, and getting their love and acceptance at Sunset on the Beach just tells us we are doing a good job," he said.