I Hate Dead People (Too): Book 2.5 of the Hellion Harlot Collection

Victory should taste sweeter than this. 
Fresh from barely surviving the ultimatum of her life, immortal witch October Winters is sentenced to Hell—the one place she’s spent centuries avoiding. She’s trapped below until she can break the curse she put on the Devil’s most diabolical sons: the Demons of Nightmares and Fear.
 
But the Primes aren’t the only creatures haunting her infernal stay: the souls she’s reaped want revenge. With a phonebook of enemies both above and below, October is assigned a bodyguard—Mayhem, a high-level Chaos demon as unstable as his name suggests. As if an unhinged protector wasn’t enough, vengeful spirits are closing in, led by Summer Jones, a fallen rockstar from the Halloween concert October destroyed just days prior.
 
Caught between a vindictive ghost, chaotic company, and an unbreakable curse, October must find a way to free the Devil’s twins and return them to the human realm so she can enjoy some well-deserved peace and quiet. But the nightmares lurking in Hell’s shadows are nothing compared to the truth she uncovers about her own past—and the real reason the Devil gave her that damn ultimatum.