
A plot to steal a top-secret instrument vital to the United States space program poses a challenging case for Frank and Joe Hardy. After rescuing a South American stowaway who mutters a warning about "Footprints " and then vanishes, Frank and Joe discover that documents belonging...

Footprints lead to the breakup of a ring smuggling Chinese aliens. Published originally in 1933.










![Footprints Under the Window [Unknown] B00139OH8I Book Cover](https://m.media-amazon.com/images/I/517xvDNttBL._SL500_.jpg)




