At a grandfather’s request, Nathan Bryce Jensen sneaked into a stranger’s house and hid.

When a man returned to the house and lay on his bed, Jensen attacked with a crowbar and insect spray.

The grandfather had told Jensen he had concerns about the welfare of the man’s child, who was his granddaughter.

So he asked Jensen to “flog” the man in a home invasion staged to look like a robbery.

Jensen did not know the man.

However the 22-year veteran plumber with no criminal history still went along with the violent plan due to a “misguided desire to help a person in need” and the grandfather’s persistence, Brisbane District Court heard on Wednesday.

“It is just extraordinary that a man of your apparent good character … engaged in this offending,” Judge John Allen said.

Jensen and the grandfather’s initial plan included breaking the man’s jaw, crown prosecutor Sam Sherrie said.

“But … (they) settled on a plan in which the defendant would sneak into the complainant’s house, flog him, steal his car and then burn the car,” he said.

After a long period of planning and surveillance, Jensen went to the man’s residence north of Brisbane in April 2022 and waited.

He entered the Caboolture South house and hid when the man left to return the child to his ex-partner, who was the granddad’s daughter.

When the man returned and lay on his bed, Jensen emerged and sprayed insect repellent into his face before hitting him repeatedly in the head with the crowbar.

With his head bleeding, the man was placed in a choke hold but managed to fight Jensen off and run outside.

Jensen grabbed the man’s car keys and followed, again hitting him with the crowbar multiple times when he tried to stop him taking the vehicle.

The man disarmed Jensen who fled and was later found hiding in bushes by police.

Jensen had zip ties, a pocket knife, a map with a route to the man’s residence, latex gloves and the car keys.

The man suffered seven scalp lacerations that required staples.

“No doubt it would have been a terrifying experience for the complainant,” Judge Allen said.

Jensen was very remorseful after about 15 months in pre-sentence custody, the court heard.

“They (offences) stem from an utterly misconceived sense of duty or obligation that he thought he held to prevent further harm happening to another,” defence barrister Ben Dighton said.

Jensen, 48, pleaded guilty to charges including malicious act with intent and administering poison with intent to harm.

“It concerns me that the extent of premeditation and violence involved in this might demonstrate a dark aspect of your character which has previously not come to light,” Judge Allen said.

“But I am prepared to sentence you on the basis that this offending was completely out of character.

“It occurred in particular circumstances where someone played upon your concerns for someone they painted as a vulnerable victim.”

Jensen received a suspended three-and-a-half year jail sentence.

-AAP