This is an oldie from 1999 and one of the first movies Jessica Alba entered. She is not the main character, she is the damsel in distress.
It's a great comedy with horror elements. So, what's the story about, well it's about a regular shy guy who suffers a possession of some sorts and he can' control his hand and it starts killing his family and friends. It's also a romantic , comedy since everything is done to make you laugh and squish at the same time.
Seth Green & Eden Henson (the friends) portray their paper flawlessly, always making you laugh when they are in. The main character is truly the main character and steals the show. Even Jessica Alba sexiness pales to compare to his job.
There isn't much I can tell you about the novel, it's basically that, it's jumping from one scene while the hand first attached and later un-attached (think of the Thing in Adams Family) try to murder the maximum of people... The question I have is, why his friends came to life? Was it the magic of the hand? But then, why the family didn't?