Susan is eventually sent to retrieve anti-radiation drugs from the TARDIS, the Doctors realizes this was what the box contained, where she encounters a second species, the Thals, who used to be at war with the Daleks.
Susan is eventually sent to retrieve anti-radiation drugs from the TARDIS, the Doctors realizes. This was. The box contained. She encounters a second species. A second species is the Thals. A second species, the Thals used to be at war with the Daleks.