The Detective & The Unicorn, Michael Angel

LAPD Detective Derek Ridder has a new partner...one with cloven hooves, a palomino coat, and a spiral horn!
Three years ago, the President welcomed a pegasus, a dryad, and a pair of griffins to the White House. Their arrival became a cultural touchstone like the Kennedy assassination, the moon landing, or 9-11. Between the somber blue-black suits of the President's cabinet and the Renaissance Faire medievalism of the creatures from the 'Morning Land', it was Norman Rockwell meets the cast of Narnia.
All creatures from the Morning Land seem peaceful enough... Until an evil wizard from that magical realm murders Ridder's friend in cold blood right before the police detective's eyes. Devastated, Ridder thinks he'll be taken off the LAPD's Homicide detail until he's given unexpected news. He's put on the wizard's trail and given a new partner: a brash, driven unicorn filly named Tavia, the Daughter of the Warder of Cavilad.
The unicorn's on a desperate mission of her own. Tavia identifies Ridder's murderer as the wizard who nearly destroyed the realms of the unicorns, dryads, and pegasi in a horrific act of war: Sir William Teach. And she's pledged her very life to capture or kill this magic-using war criminal at all cost!
Together, Derek and Tavia race to stop the wizard's demonic plans. Their path takes them through the gritty underside of Los Angeles and deep into the fantasy realm of Tavia's magical homeworld. Along the way, they encounter the wizard's world-destroying allies, learn how a police detective can learn magic, and discover whether one really needs to be virgin-pure in order to touch a unicorn mare.
Warlord and wizard, ally to demon and hellhound... William Teach isn't about to be taken down without a fight. But even with the help of a diplomat pegasus, an Amazonian tribe of dryads, and a SWAT-team's worth of cops and agents from the Secret Service, the odds are long at best.