This consists of the chord IV, followed by a return towards I using the circle of 4ths, e.g:
IV - IIIx - VIx - ii - V - I
The IV chord is diatonic to the key, but also stands for IVx, which is a substitution for VIIx.
The chords in the sequence may be used diatonically (i.e. IV - iii - vi - ii - V - I) or changed to dominants as above.
references:
There Will Never Be Another You