Two men have been arrested by detectives investigating the disappearance of a 71-year-old woman.
Louise Kam was last seen by a family member near The Spires shopping centre in Barnet, north-west London, at about 12:30 BST on Monday.
Her disappearance is said to be "entirely out of character".
The Met said it was not releasing what the men have been arrested on suspicion for and they remain in custody.
Ms Kam, from Potters Bar, Hertfordshire, has been described as a Chinese woman with very long black hair, brown eyes, of slim build and about 5ft 4in (1.6m) tall.
She usually dresses smartly and often carries a red handbag, the Met added.
Ms Kam had been driving a black BMW 3 Series convertible with the registration LM11 ECJ, and is believed to have driven from Borehamwood to Barnet before making her way to the Willesden High Road area on Monday afternoon.
The vehicle was recovered by police in north-west London on Wednesday and officers are keen to hear from anyone who may have seen it earlier in the week.
Det Ch Insp Brian Howie, from Specialist Crime, said: "Her family - in particular her two sons - are extremely worried about her.
"Officers are also becoming increasingly concerned for Louise's safety.
"It is vital that anyone who knows anything gets in touch with police or Crimestoppers as a matter of urgency."