A man who beat his partner and her toddler while driving, later ordered them to undress because they were covered in blood.

Calvin Charles Zabell, 20, rained blows on his partner as he drove from Lower Hutt to Masterton on February 8, knocking her head repeatedly into the passenger's window.

He continued punching her after she climbed into the backseat to escape, and also hit the woman's three-year-old boy.

When he eventually stopped the car he dragged the woman into the house by her hair, and later ''backhanded'' his mother.

Today at Masterton District Court Sergeant Garry Wilson said an argument over possession of a camera soon turned violent as Zabell drove along State Highway 2.

''The victim was punched repeatedly about the head and face, her head coming into contact with the passenger window with the force of the blows.''

Zabell then threatened to kill the victim and her son, and refused to stop the car.

When he eventually pulled up to a High St, Masterton address he dragged the victim into the house by her hair, Mr Wilson said.

''He told the victim to take off her clothes and her son's as they were covered in blood.''

The woman fled to a nearby pub for help, while in the meantime Zabell's mother turned up.

He struck her in the jaw before she managed to drive the victim and the victim's son away.

Zabell then snapped his partner's mobile phone and removed the batteries from her camera.

Mr Wilson said after he was arrested a police search of his car discovered an aluminium baseball bat.

This morning Zabell pleaded guilty to charges of male assaults female, assault on a child, assault, threatening to kill, possession of a weapon, wilful damage and theft.

Judge Pat Grace ordered an alcohol and drug assessment and also a report into the possibility of home detention.

''But in my view with that sort of violence the chances of you being released on a community-based sentence are slim,'' he said.

He convicted Zabell and remanded him in custody for sentencing in April.

- © Fairfax NZ News