Ab Locrian scale on the guitar fretboard
The Ab Locrian scale is made of Ab (the root), Bbb (minor second), Cb (minor third), Db (perfect fourth), Ebb (diminished fifth), Fb (minor sixth) and Gb (minor seventh). The fretboard shows every one of them across the neck in standard tuning (E A D G B E), and plays them back so you can hear the scale.
The Locrian mode is the seventh mode of the major scale, with a lowered second and a lowered fifth. The lowered fifth takes away the stable fifth above the root, so it sounds unsettled. It shares its notes with a major scale a semitone above.