Police are concerned for the safety of a South Korean tourist who has gone missing in London.
Hoyeon Jang, 75, was separated from her husband and son when she boarded a Northern Line train without them at Embankment station on Thursday.
They signalled to her to get off at Charing Cross, the next station, but could not find her there or at Archway station.
Mrs Jang does not speak English and does not have a phone or money.
The Met Police said she is described as 4ft 11in tall with short black hair. She was last seen wearing a yellow jacket and blue trainers.
She was last seen at Embankment station at about 17:00 BST and was reported missing to the force about three hours later.
The family had been visiting relatives in London.