 In its final story — "Last of the Time Lords", Martha was separated from the Doctor for a year, and after saving the world she decided to return to Earth to allow herself to qualify as a medical doctor, look after her devastated family, and get over the Doctor's inability to reciprocate her feelings.Following the airdate of "Last of the Time Lords", the BBC announced that the character would return to screens in three episodes of "Torchwood" Series 2, before rejoining David Tennant's Tenth Doctor alongside new companion Donna Noble (Catherine Tate) for five episodes in the fourth series of "Doctor Who".Appearing in "Torchwood", it is explained through exposition that Martha is a medical specialist for UNIT, a qualified doctor and "bona fide" expert on alien life.