Lieutenant Commander Steve McGarrett is the leader of Hawaii Five-O, a Hawaii State Police Department Unit based on all seven Hawaii islands. He has also served in Naval Intelligence. Five-O can mobilize and draw support from the local police departments and seal harbors and airports. McGarret grew up with his sister, Mary Ann. Steve's father was killed by criminals and after that life took a turn for the worst. He contracted polio as a child but ended up not having any permanent physical damage.