CBS is noted for its successful hit “Hawaii Five-O” which is a remake of the 1968-80 series of the same name. The show focuses on Steve McGarrett and his unorthodox team that takes on various cases that have involved murder, drugs, and disappearances. "Hawaii Five-O" is no stranger to casting shake-ups with cast members coming and going during the nine-season run.

After losing two primary cast members following season seven, the show gained two new faces in season eight. Daniel Dae Kim and Grace Park left the series following the season seven finale with their characters being written off and haven’t been seen since.

Masi Oka also left the series in the middle of season seven.

Beulah Koale and Meaghan Rath joined season eight as two new characters while several of the recurring stars were upped to series regular. Katrina Law (“Arrow”) has been announced as joining the upcoming season as a series regular. It’s been reported by Deadline that Law will be playing Quinn Liu who is a former staff sergeant for Army CID and shares that showrunner Peter Lenkov teases that fans will love seeing how she first encounters Steve and Danny.

Alex O’Loughlin (Steve McGarrett) has written and directed an upcoming episode that has been teased by Lenkov with a photo of the actor on Instagram. The episode has scenes filmed in Los Angeles and is described as being pretty emotional.

CBS has released a few photos for the season ten premiere that features new cast member Katrina Law with O'Loughlin. The synopsis for the premiere episode teases that mob bosses are being targeted which finds Five-O working with a new ally to solve the case. The team will also be losing one of their own in the show's return but no hints have been given as to who might be leaving.

Higgins has a choice to make

Magnum PI” premiered last fall and has direct connections to "Hawaii Five-O" with the same setting and familiar faces. The original series starred Tom Selleck and aired during the 1980s. The new series has Jay Hernandez in the lead role and is about Thomas Magnum who does private security for Robin Masters while also working as a private investigator.

He often turns to his two closest friends for help and has teamed up with Juliet Higgins who works for Robin and doesn't particularly like Magnum.

The two bicker most of the time but Magnum is never shy about asking her for her MI6 experience (and computer) for various cases. CBS has released several teaser photos from the premiere episode that tease Magnum back to work with his friends. The synopsis teases Mangum trying to find a missing woman that witnessed the murder of her boss. The episode will also see two of the characters making big decisions as Higgins still hasn’t made a choice about becoming Magnum's partner and Rick makes a decision about his career.

Crossover plans

Hawaii Five-O” is going into season ten while “Magnum PI” is going into season two.

“Magnum PI” has moved to Fridays joining the line up with “Hawaii Five-O” and “Blue Bloods." Filming has already gone underway with the "Hawaii Five-O" castmates kicking things off with a blessing ceremony. “MacGyver” is noticeably absent from the schedule and it has been confirmed that it will not air during the fall season instead will air in 2020. An air date has yet to be announced.

Since “Magnum PI” was first announced fans have wished for a crossover between the two shows. This dream will soon become a reality as Peter Lenkov shares with TVLine that he has plans to make a crossover happen this season sooner rather than later and the writers have even narrowed down a story. When the crossover does air, it will consist of two parts and will air back to back.

However, “Hawaii Five-O” characters have already made appearances throughout the first season of “Magnum." Taylor Willy, Dennis Chun, and Kimee Balmilero have all reprised their roles from "Hawaii" for various episodes and are set to return to “Magnum” for season two. They’ll also remain on “Hawaii Five-O.” The second season of "Magnum" will also see Shawn Mokuahi Garnett and William Forsythe paying a visit as their "Hawaii" characters.