This is the shocking moment a robber waves a knife at a shopkeeper and his teenage son in Hillingdon as he forces the father to open his till.
Detectives have released the footage in a bid to catch the man behind the terrifying raid at Taal Food and Wine in Ruislip .
Police said they were called to the store in Field End Road, where a "substantial amount" of cash was taken, on Saturday, May 14, at around 10.35pm.
CCTV footage shows the robber holding a large kitchen knife close to the face of the 49-year-old shopkeeper as he forces him to open the cash register.
Officers said the shopkeeper had earlier received cuts to his hands as he tried to protect himself and his son, who was pinned down in the corner of the shop during a struggle with the attacker.
Police said the robber held the knife to the shopkeeper's throat and that of his son when he tried to escape.
The owner of the shop was taken to a west London hospital for treatment and was later discharged.
The suspect is described as a tall Asian man, aged in his mid 30s, and of medium build. He was wearing a grey cap, blue work overalls and dark trainers.
Anyone who recognises him or has any information is asked to call police on 101 or 020 8246 1413, quoting reference 0909609/16. You can also call Crimestoppers, anonymously, on 0800 555 111.