Laurence Bedard as Kathleen "Katie" Lee Mcgarrett Olinsky. (Danny Williams)

Scott Caan as Daniel "Danny" Williams. (Katie McGarrett)

Valerie Cossette as April "Aj" Jeanette Williams Voight. (Steve McGarrett) ElleVoight

Alex O'Loughlin as Steven "Steve" McGarrett. (Aj Williams)

Hawaii Five-O cast as themselves. (Adam, Lou, Tani, Junior, Jerry, Kamekona, Grace, Charlie, Catherine, Quinn, Chin, and Kono)

Mila Stauffer as Callie Rae Maloley.

Carrington Durham as Kacey Stevens. (Friend of Katie & Aj)

Chicago PD as themselves.

***