  We report evidence for a quasi-periodic oscillation (QPO) in the optical
light curve of KIC 9650712, a narrow-line Seyfert 1 galaxy in the original
Kepler field. After the development and application of a pipeline for Kepler
data specific to active galactic nuclei (AGN), one of our sample of 21 AGN
selected by infrared photometry and X-ray flux demonstrates a peak in the power
spectrum at log $\nu$ = -6.58 Hz, corresponding to a temporal period of t=44
days. We note that although the power spectrum is well-fit by a model
consisting of a Lorentzian and a single power law, alternative continuum models
cannot be ruled out. From optical spectroscopy, we measure the black hole mass
of this AGN as log $M_{\mathrm{BH}} / M_\odot$ = 8.17. We find that this
frequency lies along a correlation between low-frequency QPOs and black hole
mass from stellar and intermediate mass black holes to AGN, similar to the
known correlation in high-frequency QPOs.
