It all happens so quickly.
This shocking CCTV footage shows a young family walking through a shopping centre in Derby, East Midlands.
At one point, the unnamed mother walks very slightly ahead of her child.
Seconds later, a man - dressed in a dark jacket and cap - appears and approaches the 22-month-old boy as he follows his mother into a store.
The stranger walks up to the boy, speaks with him for a moment and then takes him by the hand, walking off.
Thank goodness the mother turned around and spotted him, challenging the man and driving him away from her young son.
Officers are now questioning a man, who rang police after seeing the footage online, following the incident.
Detective Chief Inspector Nick Lamb, of Derby Police, said: "This was a very isolated and extremely unusual incident and we are very keen to speak to the person shown in the images.
"Although we do not know the intentions of the man involved, I would urge parents or those with young children to always be mindful of their safety, especially in crowded places."
Anyone who recognises the man is asked to contact Derbyshire Police.