Based on the graphic novel from bestselling author Grant Morrison and artist Darick Robertson, "Happy!" follows Nick Sax (Christopher Meloni), a former cop turned hit-man living a depraved life of booze and murder. After a botched hit, Nick’s life is irrevocably transformed by the sudden appearance of a tiny, imaginary and incessantly cheerful blue-winged horse named Happy (voiced by Patton Oswalt).