A teenage boy whose family were being robbed at gunpoint alerted neighbours by texting them while his hands were handcuffed behind his back.
The 16-year-old managed to slip his mobile phone from his pocket and type the words: "Call police to my house - we are being robbed."
He even managed to dial the neighbour's number so his mother could lie next to him and whisper into the mouthpiece.
Four men had burst in to the house in Hendon, north west London, on a Saturday night in April, armed with two guns and a screwdriver.
They punched the mother in the face and kicked her daughter in the head, before herding the family and their housekeeper into a bathroom where they bound them and forced them to lie on the floor.
The 49-year-old woman, speaking for the first time this week, said: "My son was amazing. He kept his wits about him and took in everything that was happening. I'm very proud.
"The gang told us to lie on the floor and be quiet. A couple of minutes later one came back to check on us. We couldn't speak because we thought they would come back again.
"He texted the neighbour and then put the neighbour's number on it. I managed to call and whispered, but I had to ring off because we heard a noise. My neighbour told me later she had already called the police because she guessed something was wrong.
"He goes to an Orthodox school and they teach themselves to text with their phones in their pockets. It came in very handy."
The gang broke in at about 11pm after the mother had gone to bed. They pounced on her son, handcuffed him and marched him to his mother's bedroom, where she, too, was handcuffed.
The mother, who was punched in the face for at first refusing to tell the raiders where the safe was, said: "My youngest son, who is seven, was asleep in my bed.
"They threatened to either take him with them or cut his throat if I didn't tell them where the safe was. That was one of the worst moments.
"If I had been alone, I might have acted differently, but there were too many children around for me to do anything rash." Her youngest child, a son aged seven, was asleep in her bed. Two others, a boy of nine and a girl of 11, were asleep in other rooms.
At one point, the family's 21-year-old daughter arrived home unexpectedly.
She said: "I came back with my boyfriend to get my student identity card. The lights were on but it was very quiet. I went up to my room and thought I would say hello to my mum on the way down.
"I picked up my identity card, turned around, and a man was standing in the doorway pointing a gun at me. I didn't freak. I convinced myself it wasn't real. I thought it was a joke - but then I realised I didn't know any black people, so I knew it was real.
"They took me downstairs and told me to tell my mum to open the safe. Then one of them kicked me in the head and my chin hit the wooden floor. I had a bruise for a week."
Her boyfriend became suspicious when she didn't return to his car outside. The 25-year-old investment banker said: "I knew something was wrong because she should have been in and out.
"I went to a neighbour and told them to call the police. Then I called a friend and told him to bring something to defend myself. He brought me a tennis racket.
"I knocked on the door but no-one answered, so I kicked it down. I shouted but no-one answered. I went upstairs and shouted again but still no-one answered. Then I heard her call out and I found them."
The mother said: "We heard a crash and thought the gang were still there, so we daren't move or speak. Then we heard my daughter's name being called so we knew it was her boyfriend. What he didn't know was the gang had already gone."
The gang, all Afro-Caribbean, aged about 20 and wearing balaclavas, took jewellery the mother was wearing, as well as a number of other expensive items and cash totalling £60,000.
Det Sgt Paul Richardson of Barnet CID said: "This was a horrible ordeal an innocent family were forced to endure in their own home. We are making every effort to arrest those responsible."