If there is one element of “Hawaii Five-0” that has helped sustain the show for 10 seasons, it could be the story of Steve McGarrett and the fundamental characteristics and qualities that make him such a great character to watch. The complex DNA of McGarrett, played by Alex O’Loughlin — his loyalty and faith in others, his strong conviction and his love for his ʻohana, and his deep compassion for the downtrodden, are just a few of the reasons why McGarrett is such a force to reckon with.

This week’s episode titled “Ka ʻiʻo,” which loosely means “DNA” in Hawaiian, is perhaps the most anticipated episode of this season. In Hawaiian “ʻiʻo” literally means “flesh, meat, flesh and blood, muscle, sinew, essence, substance.” As there is no direct translation of DNA in our language (the term Deoxyribonucleic acid, or DNA, would just be pronounced dēnūʻā by Hawaiians), the idea of something that is part of your flesh and blood and entwined within your very essence would make complete sense to Hawaiians.

Written and directed by series star Alex O’Loughlin, the episode was explosively dramatic, both literally and metaphorically. O’Loughlin takes his character and McGarrett’s mother, Doris (Christine Lahti), on the final leg of their journey together and puts to rest the story of Shelburne, his mother’s CIA operative handle.

Sadly, it doesn’t end well for Doris, and once again, McGarrett has been left emotionally adrift. But the episode itself is a tour de force for O’Loughlin, as it shows his skill behind the pen, as well as his expertise as an actor and director. Like the 100th and 200th episodes, this one helps to mark “Hawaii Five-0” into legendary status.

McGARRETT’S DNA

The story starts with McGarrett in a difficult situation when he is asked by CIA Agent Coen (Taylor Handley) to get his mother out of Mexico, where Shelburne has supposedly gone rogue. The CIA thinks that Doris fell in love with her intended target Carmen Lucia Perez, part of the Sinaloa cartel, and killed her CIA partner. Now the government wants McGarrett to get their agent and kill Lucia, telling him if he declines their proposition, they “can’t promise this will end well” for his mother.

McGarrett tells Coen that Doris “gave up her life for this country and gave up her family for your agency.” But that doesn’t seem to matter to the CIA and McGarrett doesn’t have much choice but to go underground and find her. He must do it without the help and back up of Five-0, much to the dismay of Danny (Scott Caan). Even his SEAL brother Junior (Beulah Koale) can’t help him until McGarrett reaches out for his help.

All of this leaves both Danny and Junior, as well as the rest of the team, Lou (Chi McBride), Adam (Ian Anthony Dale), and Tani (Meaghan Rath), feeling scared and uneasy. But Danny and Lou are right, it’s McGarrett’s mother. He’s going to do what he has to do and if he “doesn’t go he’ll regret it for the rest of his life.” Danny specifically knows McGarrett is always going to risk his life for someone he loves, especially if it means bringing his mother home and finding her justice. It is in McGarrett’s DNA to do this, no matter the cost.

SHELBURNE’S SECRETS

McGarrett takes a very long and dangerous route to Mexico to find Doris. He survives long enough to find his mom and reaches out after surveilling her movements, to get her to leave with him. All McGarrett gets for his trouble is being pistol-whipped by his mommy and told to go home. Junior arrives to cover his six, and brings with him two other SEAL brothers, Mike (Stephen Paul Kaplan) and Ethan (James Beck) to help. Their little team concocts a plan to not only get Doris back but one that will stop a container ship full of cocaine from getting into the Sinaloa cartel’s hands.

The operation is very explosive, as McGarrett’s team needs to take on a large number of men in order to get to Doris. Once McGarrett finds Doris, their showdown between mother and son is shockingly painful. Not only does McGarrett think Doris is going to shoot her own son, but they both don’t seem to understand the wants of each other.

Doris tries to explain to Steve what he has done to jeopardize her plans. After so many years spent underground away from her family, losing her husband and not seeing her own grandchild, the experience has taken a toll on Doris. She thinks if she gets this last payoff she can set up Steve, Mary, and little Joanie financially.

She wants to take care of them, no matter what happens to her — even if she is disavowed by the government, killed or imprisoned. She seems to have wanted to do something good with her life and for her children. Before Doris can tell her son what her plans are, Lucia shoots him and guts Doris with a knife. Junior kills Lucia, but not in time to save Doris, who dies after she apologizes to McGarrett and tells him she loves him.

LIFE ON LIFE’S TERMS OR NOT AT ALL

Earlier in the episode, Steve has a dream that Doris is reading him “Moby Dick” yet he can’t hear her, and she cannot hear him. She kisses him goodbye and leaves, which haunts him the entire time he is hiding in Sinaloa. The dream also reflects a major theme in the book which deals with “perception between seeing and understanding, which makes deep reality hard to discover and truth hard to pin down.” Perhaps finally facing Doris, and hearing her rationale for her actions may have given McGarrett some part of her truth which was always very difficult for him to pin down.

But maybe he is right as he tells Danny after Doris’s death that he now understands that “none of this is on our terms … it’s life on life’s terms or not at all.” Perhaps McGarrett will find a way to be able to move on instead of feeling like he has been left to swing out in the darkness. But no matter what, after two shattering deaths in his life, McGarrrett needs something to bring him back. We can only hope that his friends and Five-0 are enough.

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