Tangra: A 21-year-old woman grabbed an Uber driver's cellphone off the dashboard and tried to break a windowpane so she could call for help after the car veered off the route and drove along Tangra's narrow, dark lanes for half an hour on Saturday evening.

She failed to break the glass but succeeded in unlocking the left front door as the cab slowed, jumped out and shouted for help. Residents intercepted the cab and informed police.

Keshab Prasad, the driver, has been arrested on kidnapping charges and remanded in five days' police custody.

The woman, who recently graduated, told this newspaper: "I had gone to Shyambazar to lunch with a friend. I booked an Uber pool cab around 5.10pm. Two men were in the rear seat, so I took the front seat."

One of the male passengers got off at Fariapukur and the other somewhere on Bidhan Sarani.

"From the Sealdah flyover, the cab took a sudden left (towards Tangra) instead of going straight ahead to the Moulali crossing and taking CIT Road," the resident of Gobra Road in Beniapukur said. "I asked the driver why, but he did not reply and kept driving."

She said she was not familiar with the route the cab had taken. "He kept changing roads till we entered a narrow alley. All this while, he mostly ignored my questions. When I shouted that I needed an explanation, he said this was the route to my home," she said.

"I searched for the knob to roll the window down - but it was a power window, with the switch on the driver's side. If there was a switch on my side, I was too nervous to find it."

She called her mother from her cellphone. "Her phone kept ringing. I realised she was busy, and got even more scared," she said.

"Suddenly I noticed the driver's phone on a stand on the dashboard. I grabbed it and started hitting the windowpane with it to try and smash it and catch the attention of other motorists or the pedestrians."

The driver, she said, tried to snatch the phone back and it dropped to the floor. "He slowed the car. I somehow unlocked the door and jumped out," she said.

"I had no idea where I was. There were three men standing on the pavement; I shouted to them and they intercepted the car. I told them everything and called my mother, asking her to come."

The woman said she did not know about the panic button, the red button between the two front seats that is also within reach of any backseat passenger. If pressed, it sets off a siren-like wail that cannot be silenced unless the cab is stopped and the bonnet opened.

Nor did she know about the city police's Bondhu app, integrated with the Uber app, which allows a rider to directly contact the police control room with a tap.

An Uber spokesperson said: "What's been described today is deeply upsetting. We are looking into the incident and will provide full support to law enforcement as and when required."