Grant Newbury (Tom Mix), Deputy Inspector of Immigration at the US/Mexico border is asked by his boss to infiltrate a gang smuggling Chinese workers through the border at Calexico, in order to identify and arrest their ringleader.
Meanwhile, in Chicago, Estelle Halloway (Eva Novak) is disappointed because her guardian wrote that she would not be able to spend her holidays with him in Calexico as planned.
When she wires him that she will come nevertheless with her roommate Marguerite (Adele Warner) and her brother (William Buckley), he tells her that they will meet instead near the Grand Canyon as it is too warm in Calexico.

In Calexico Grant finds out that the ringleader is none other than Jim Frazer (J. Farrell MacDonald), Estelle's guardian.
He becomes part of the gang and is requested to go and help taking of the Chinese now hidden in a camp in Grand Canyon.
After having left discreetly the camp to fetch the police, he sees Estelle on the point of drowning in a river and saves her.
He is caught by the bandit who have learned that he is a government agent but manages to escape first on horseback then in a motor car and reaches the little town of Williams where he gets the help of the police.

While the police drives to the hidden camp in motor cars, Grant borrows an aircraft and flies into the Grand Canyon where he jumps in a river and manages to free Estelle.
Jim Frazer is identified as the ringleader and arrested, but  to protect Estelle, Grant accepts that he lets her believe that he is leaving for a long trip.
Frazer asks Grant whether he would help take care of Estelle while he is in jail and Grant answers: "I'll look after her the rest of her life if she'll let me."
Grant Newbury (Tom Mix), Deputy Inspector of Immigration at the US/Mexico border is asked by his boss to infiltrate a gang smuggling Chinese workers through the border at Calexico, in order to identify and arrest their ringleader. Meanwhile, in Chicago, Estelle Halloway (Eva Novak) is disappointed because her guardian wrote that she would not be able to spend her holidays with him in Calexico as planned. When she wires him that she will come nevertheless with her roommate Marguerite (Adele Warner) and her brother (William Buckley), he tells her that they will meet instead near the Grand Canyon as it is too warm in Calexico.
In Calexico Grant finds out that the ringleader is none other than Jim Frazer (J. Farrell MacDonald), Estelle's guardian. He becomes part of the gang and is requested to go and help taking of the Chinese now hidden in a camp in Grand Canyon. After having left discreetly the camp to fetch the police, he sees Estelle on the point of drowning in a river and saves her. He is caught by the bandit who have learned that he is a government agent but manages to escape first on horseback then in a motor car and reaches the little town of Williams where he gets the help of the police.
While the police drives to the hidden camp in motor cars, Grant borrows an aircraft and flies into the Grand Canyon where he jumps in a river and manages to free Estelle. Jim Frazer is identified as the ringleader and arrested, but  to protect Estelle, Grant accepts that he lets her believe that he is leaving for a long trip. Frazer asks Grant whether he would help take care of Estelle while he is in jail and Grant answers: "I'll look after her the rest of her life if she'll let me."
Sky High (1922 film)