Every girl needs a best friend and Samantha is Madeline’s best friend. She’s just as smart as Maddie, but a little older and wiser when it comes to the opposite sex. She’s quick to call General Minter out on his obnoxious behavior and is totally loyal to Maddie. Keira Knightly, best known for her role in “Pirates of the Caribbean” has the look for “Samantha.” She’s smart and savvy, able to hold her own in any lab. Samantha requires a lot of guts and Keira has that in spades.