The stranger didn't know the prearranged code word when the 10-year-old girl asked him. So she knew something was wrong.
And for good measure, as the would-be abductor and his companion drove away, the girl was able to memorize part of their vehicle's licence plate.
"She was able to give a pretty good description of both the male and the vehicle," said Detective Dave Mason of Durham Regional Police.
"All very intelligent."
The foiled kidnapping unfolded Monday afternoon in Ajax, just east of Toronto, when the unidentified couple tried to abduct the girl outside her elementary school.
She was leaving Applecroft Public School, near Magill Drive and Westney Road, around 3:30 p.m. when she was accosted by a man who told her he'd been asked by her mother to collect her.
He then gestured toward a car in the school parking lot, in which a woman was in the passenger seat.
The girl paused.
And then a procedure she had worked out with her parents kicked in, devised for precisely such a situation.
If we ever send someone to pick you up, she'd been instructed, we'll tell them the code word. Before you go anywhere with them, ask what it is.
"She asked the person and they said the wrong code word," Det. Mason said.
So instead of getting in, the girl quickly spoke to her parents, who contacted police.
The couple's car - which the girl believes she'd seen before - was a small, two-door sedan, grey/ blue in colour with a conspicuous dent on its rear bumper, just left of the licence plate.
And as it vanished, the child glimpsed some of the plate's letters and numbers.
The man police are now seeking is described as white, with a medium build and unshaven. He was wearing a grey hat, a blue scarf, a green jacket and distinctive red-and-black high-top sneakers.
His companion was also white, possibly in her late teens or early 20s, with long blonde hair. She was wearing a purple and pink hat.
"We're still in the process of trying to figure out who this person is, and maybe get a better description," Det. Mason said of the man.
The licence plate letters were not quite correct, he said, so police are now running through various possible combinations
As for the child, "she's fine.. it's all just a good example of safety planning."
Anyone with information about the incident is being asked to call Detective Mason at 1-888-579-1520 ext. 2541.