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. First appearing on the spin-off series in "Torchwood" episode "Reset", fellow companion Jack Harkness establishes Martha's credibility to her new peers, slyly commenting upon her vast experience. John Barrowman noted that in many ways Martha entered Torchwood as their superior as being employed with UNIT placed her in a higher authority. In the same episode, Martha notes that an "impeccable source" recommended her employment to UNIT, implying the Doctor holds the highest level of faith in Martha's capability. Her Torchwood outfit was specifically designed to reflect her development, with Costume designer Ray Holman stating: "We wanted to give her that air of authority, with some professional-looking and quite classy fitted suits".