A consumer has discovered pills, believed to be ecstasy tablets, inside the box of a pre-owned copy of Grand Theft Auto IV.
Richard Thornhill bought the title from a Gamestation store in Gloucestershire and found the pills inside the box - wrapped in cling film - which he delivered to a nearby police station.
He was offered an apology by the store, but expressed his fear over concerns that his 12 year-old son or 16 year-old daughter could have been harmed.
"When I opened the box up, the cling film wrap fell out. I could not believe it," he told the Telegraph. "I have two children and my son plays Xbox all the time. He could easily have opened the box and found them.
"I dread to think what the consequences would have been if he had. He is only 12. He could have died.
"It was a pre-used game, but that should not make a difference," he said. "My wife is beside herself over this because she keeps thinking about what could have happened and so do I."
Gamestation commented: "We have rigorous procedures for accepting pre-owned titles and checking them before they are put back on sale.
"We have launched an immediate investigation and we will work closely with police to find out what happened in this instance. It would be inappropriate to comment further until the police investigation is complete."
Gloucestershire police said: "We have collected the tablets and will be destroying them at a later date. It is likely that they are ecstasy pills.
"We are now conducting enquiries to see if it can be established who brought them into the store."