Young Lauchlin Mackinnon has to leave the family tenement to seek his fortune. After finding and losing various employments in 19th Century Edinburgh he is encouraged to join the army and becomes involved in the British re-capture of the Cape of Good Hope. However, Vice Admiral Home Popham chooses to disregard his orders and invades the Spanish Vice-royalty of the River Plate. Lauchlin has many adventures in what is to become Argentina and his romantic involvement with the beautiful daughter of a leading colonist leads him to choose between returning or staying.