Caroline Young and Sally Edmonds, both 27, were left tied to a pine tree by Danny Horning, a convicted armed robber, after a 90-mile drive across Arizona.
The convict, who has been on the run for two months after escaping from jail, threatened the women with a revolver and forced them to drive him through two police roadblocks as he crouched in the back of their hire car.
Horning approached the girls as they sat in their car parked overlooking the canyon on Saturday. He told them he would not hurt them if they kept driving. Sally coolly spoke to patrol officers at one roadblock and they travelled unchallenged through a second roadblock before Horning ordered the women to drive off the highway on to a dirt track near Flagstaff, Arizona, where he tied them to a tree and fled in their car.
Detective Kathy Paleski said: 'It took them about 20 minutes to escape and then they ran back on to the highway and flagged down a motorist who drove them to a telephone where they contacted the state police.'
Their description of the car enabled police to recapture 35-year- old Horning after a chase during which he fired several shots. He has been charged with abduction.
Ms Young, from Eccleshall, Staffordshire, and Ms Edmonds, from Harborne, Birmingham, graduated in medicine from Birmingham University last month.