Jay Hernandez, Perdita Weeks, Zachary Knighton, Stephen Hill, Meaghan Rath, Katrina Law, and Beulah Koale appeared in both parts of the event as Thomas Magnum, Juliet Higgins, Orville "Rick" Wright, Theodore "TC" Calvin, Tani Rey, Quinn Liu, and Junior Reigns, respectively (Melissa Tang also guest starred in both parts as Erin Hong).

When Hong, a man that Magnum and Higgins are monitoring for a client, gets shot and killed and his killer escapes, the team from Hawaii Five-0 gets involved.

Magnum, Higgins, TC and Rick assist as the group recovers a secret list of CIA double-agents.

Soon after, Junior Reigns is kidnapped as leverage for the criminals to get the list back, leading to Magnum's team helping Tani Rey and Quinn Liu in a search-and-rescue mission.

Before the crossover, Hawaii Five-0 characters had crossed over to Magnum P.I., such as Kamekona (Taylor Wily), Duke (Dennis Chun), Noelani (Kimee Balmilero), Flippa (Shawn Mokuahi Garnett) and P.I.