One of the main themes of “Hawaii Five-0,” to its very core, is friendship. Hawaiians have a word for friendship — pilialoha — which means so much more than the basic concept of being friends or friendly with another person. “Pili” means to cling, to join or adhere; and “aloha” means love, but also compassion, mercy, sympathy, kindness, sentiment and grace — all important traits of a true friendship. It is not uncommon for McGarrett (Alex O’Loughlin) and his Five-0 teammates to go above and beyond their assigned duties to help a friend.

In this week’s episode, these bonds of pilialoha are put to the test when McGarrett breaks the rules to find out why a friend has been killed, and Adam (Ian Anthony Dale) faces both a personal and professional hurdle that puts his friendship with the team at risk. The episode title, “Aia i Hi‘ikua; i Hi‘ialo,” is Hawaiian for “Is Borne on the Back; Is Borne in the Arms.” It is a olelo noeau, or Hawaiian proverb and poetical saying, and is “said of a favorite child, who is carried in the arms or on the back.”

The phrase is a strong description, both literal and figurative, for this episode, written by Rob Hanning and Paul Grellong, and directed by Peter Weller. The main storyline has McGarrett looking into the strange death of a fellow SEAL brother, Carson Rodes (Eddie Cahill from “CSI: NY”), who days after having drinks together, turns up dead on a plane with a bullet in his gut and a baby on board.

It also helps to describe Adam, who in a sense, is a “favorite” of McGarrett and the Five-0 crew. He has strong ties to Danno (Scott Caan), who considers him to be an uncle to his children; with Tani (Meaghan Rath), as he helped save her brother’s life; and the rest of the team treat him as one of their own. Adam has returned home with bad news and does not know what Tani has discovered in his home while he was gone.

BABY ON BOARD

The case of the week starts off by showing us daily operations on the flight deck of the USS Nimitz. The crew gets a distress call from an approaching single-engine Cessna. It is Rodes and he is begging to make an emergency landing on board the aircraft carrier. He’s reluctantly allowed to land and they find him dead, bleeding from his gut, and a wailing baby in the back of the plane. It’s an exciting and mysterious start to the episode — and absolutely captures your attention. Obviously, the man flying knew he was dying and needed to save the baby from crashing and drowning in the ocean. But where did he come from, why was he shot, and who is this little baby?

McGarrett learns about Rodes’ death from NCIS Agent Emma Warren (Nazneen Contractor). Against her request to stay out of her way and let her do her job, McGarrett immediately begins to look into why his friend is dead. Lou (Chi McBride), Jerry (Jorge Garcia), Junior (Beulah Koale) and Tani are busy trying to trace the plane and search for missing babies. They need to know where he possibly could have taken off from in order to land on the Nimitz. Jerry and Lou take a field trip to where the plane is being held and con their way into the hangar — Jerry posing as a maintenance crewman, and Lou as an NTSB agent. Jerry is always perfect playing the fall guy — and Lou with his demanding presence uses Jerry’s diversion to get the tail number of the plane.

MCGARRETT ARRESTED

All along NCIS thinks that Rodes was doing some dirty work and perhaps kidnapped the baby. McGarrett swears that Rodes was a good guy — he served with him on two tours; he knows his friend. McGarrett is devastated by his death, and despite Warren’s warning to stay out of the investigation, he goes to search Rodes’ hotel room. He finds a license plate number written on a piece of scrap paper taped to the underside of a bedside table. It’s an old trick Rodes taught him called “The Tape Trick” which they used to do if they felt they might be in danger. The license leads them to a rental car, which then gives them a phone number — which routes them to Lanai. Lanai is also where Rodes took off from that morning headed to Oahu.

Unfortunately, this gives Warren the means to arrest McGarrett for, as Danno gleefully counts off for her, “crossing the crime scene tape at the hotel room; tampering with evidence from an active investigation; lying about it; lying about it again.” It’s hilarious how much joy Danno gets from watching McGarrett be arrested, probably because he knows the governor will get him out of this little jam — but not before Danno gets to see McG in handcuffs.

It’s not like McGarrett hasn’t been arrested before — or Danno for that matter. It’s just that this time, Danno knows it won’t stick. And it’s not for anything like murder, which both have gone to jail for in the past. This time, it’s about playing nice with another law enforcement agency — and to clear a friend’s name.

MCGARRETT’S VINDICATION

Once McGarrett asks Warren to join forces they begin to wrap up the case. Tani and Lou fly to Lanai and find five dead bodies at a home that seems to have been where the baby and his mother, Julia Berg (Sarah Dumont), were hiding with her friend while they waited for passports to get out of the country. The bodies lead them to the house where Julia is being held, and she tells McGarrett and Warren the entire story.

It seems as if Sarah’s husband, Lee Berg (Gabriel Mann), was very abusive and Sarah was trying to get away from him before he began abusing their son. After Rodes — who was hired by Lee to get his son back — arrives to confront Julia and hears the real story of why she ran off with the baby, he tells her he will help her get away. But Lee knows Rodes is a good man and would turn on him once he found out the truth, so he sent in a group of thugs to kill Rodes and Julia and bring him the baby.

McGarrett and Warren, with the rest of the Five-0 team, chase Lee to an airfield and get baby Branden back, with an assist from Junior. It was so sweet to see Junior holding a cooing baby, who didn’t seem to know how many big huge guns had just been pointed at him. We all like happy endings, but it seemed as if McGarrett really just needed to confirm his SEAL brother was the good man he knew him to be.

DUKE IS BACK

One of the sweetest scenes was the return of Sgt. Duke Lukela (Dennis Chun) to HPD. With McGarrett leading a small crowd to greet him, Duke is all smiles as he thanks McGarrett for helping him return to duty. It was so touching when the two men salute each other and McGarrett tells Duke what a pleasure it is to see him back in uniform.

Duke obviously gets back to work soon, as he is seen later executing a warrant on Adam’s house. Duke sheepishly apologizes and tells Adam that HPD received an anonymous tip about a murder investigation and needs to search his home.

ADAM’S RETURN TO FIVE-0

Unlike Duke’s celebratory return to HPD, Adam’s reunion with Five-0 is much different. Tani finds him drunk and disheveled in his house just as she arrives to replace the gun she found in his home. In last week’s episode, she had asked Capt. Keo (Eric Steinberg) to test the gun. Keo ran ballistics on the gun and told Tani the gun was the weapon that shot Noriko Noshimuri, Adam’s long-lost, evil half-sister.

Adam is in a state and tells Tani his marriage to Kono is over. “Her job had become everything to her. And there we were. Two different people, just trying to pretend it still worked,” he admits to Tani. When she returns to Five-0 headquarters, she tells McGarrett that Adam is home, but that he and Kono have broken up. McGarrett doesn’t seem that surprised by the news but is concerned about Adam’s well-being. While McGarrett is being detained by NCIS he asks Danno to stop and see Adam.

Danno finds Adam passed out cold on his couch, still in relatively the same state Tani found him in that morning. After Danno throws a glass of water on his head and hands him a cup of coffee, he tells Adam he knows how he feels. “I’ve been there, too. When Rachel and I broke up, I was in bad shape. I was sick. I couldn’t eat. I didn’t sleep. I was a mess. But I promise you, I promise you it gets better. It will pass.”

Adam says he appreciates McGarrett sending Danno there to give him a pep talk, but Danno tells him, “The pep talk is from me. The invitation, on the other hand, that’s from Steve.” And Danno offers Adam a badge and a place with Five-0. Adam happily accepts and hugs Danno, despite Danno’s laughing remarks about how bad he smells, despite how much he loves him.

ADAM’S FATE

But how does having the murder weapon which killed his sister, who Adam said deserved more than prison, play into now being a member of a task force with immunity and means? Adam seems to have found the gun before his house is searched by Duke, and he brings it to Tani and questions her motives. He thinks she planted the gun because he says he’s never seen it before.

While she doesn’t admit to calling in the anonymous tip — she does tell Adam that his saving her brother’s life means more to her than anything he could have done. She said when she found it she thought of turning him in but she couldn’t after everything they have been through.

Yet it is Adam that brings up the biggest question of the episode: If Tani didn’t plant the gun or call in the tip, who did? We hope this gun won’t end his friendship with Five-0 and the start of his new life,

Because for Adam, if he doesn’t have his friendship with Five-0, he may have nothing left.

Wendie Burbridge writes the “Five-0 Redux” and “Magnum Reloaded” blogs for staradvertiser.com. Follow her on Twitter and Instagram.