It starts out in C# minor. Mess around with the two most common minor scales, Aeolian and Dorian, and perhaps some harmonic minor, as well as the C#m pentatonic and blues scales.

After that, it gets all jazzy and it's hard to pinpoint a definite key. Follow the chord in that part.

Quote by blue_strat
Db minor.
That's enharmonic to C# minor, but Db Minor does not have a key signature. It is generally called C#m unless you have a very compelling reason to call it Db.
^ Fair enough. I have a tendency in jazz to call things Db instead of C#, Eb instead of D# etc.