Myrtle Beach police charged two West Virginia sisters after they told officers they were robbed, then later changed their story.
Heather and Tara Crow were charged Friday with drug-related loitering with harmful intent.
Police said the pair initially told officers they were robbed about 4:30 p.m. Friday by a man who asked them for a ride.
They also said they drove to several locations at the man's request and he robbed them at the final stop.
Later, the women told police they actually met the man in a hotel, where they gave him $40 to buy marijuana, according to a police report.
The women told police they drove the man to several locations to buy drugs before stopping at a home on Chester Street, police said.
There one woman got out of the vehicle with the man and he pulled out a knife on her, demanded the rest of her money and fled, police said.
Police said the women were charged because they willfully went to an area known for drugs and prostitution intending to buy marijuana.