Emergency services contacted police at around 4.30am this morning (April 24) after a woman was found unresponsive in a hotel in New Steine, Brighton.
Police say the woman was pronounced deceased at the scene by ambulance staff.
A police spokesperson said:
"A 43-year-old man and two 41-year-old women have been arrested on suspicion of being concerned in the supply of a class A drug
"They have been taken to custody and enquiries are ongoing.
"No further information is available at this time."