School For Spirits: Archangel Undercover - Spirit School, #5

Sandalphon isn't the most popular Archangel, or the handsomest, or even the strongest, but he might be the kindest. For seven years, he's watched over his charge, a young woman named Mikayla Frost. He's dried her tears, fulfilled her wishes, and helped her make new friends, but now they're facing a new challenge: Death. Mikayla passes away just after her seventeenth birthday, leaving her beloved grandfather behind.
Even in life, Mikayla enjoyed helping people, so spirit school is right up her alley. Her instructor, "Sander Phelan, " is super cute... but he's hiding a huge secret.