A man and a woman have been arrested on suspicion of murder following the death of a woman who suffered a serious head injury in West Bromwich.
Ambulance staff alerted police to an incident at an address on High Street at about 03:15 BST on Monday.
A 26-year-old woman was taken to hospital but has since died. A post-mortem examination is due later.
A 32-year-old man and a 26-year-old woman remain in police custody.
The pair were initially arrested on suspicion of grievous bodily harm.
Det Insp Gary Dring, from West Midlands Police, said: "We are still piecing together the events leading up to this woman's tragic death and are working to establish exactly what happened.
"I am appealing for anyone who has any information about this incident or who believes they may be able to assist with this investigation to contact us."
Officers said they were not looking for anyone else in connection with the incident.