Trail of the Spellmans by Lisa Lutz

This is one of the more twisty, harder to guess Spellman books. Izzy’s family has gone nuts on her: Mom is participating in every extracurricular activity known to man, Dad is hiding something, David and Rae are fighting over something but Izzy can’t figure out what. While she’s investigating her family, she’s also got real cases going on. The main one involves her spying on a husband on behalf of his wife, but then also spying on the wife on behalf of her brother. As usual, it all works out in the end, but it’s a screwy ride getting there!

A major point of humor in this book is Izzy’s interactions with her niece Sydney, aka Princess Banana (you’ll find out why). A sample:

“David’s brow unfurled and he crouched down on the floor with his daughter. ‘Did you have a fun time with your aunt Izzy?’ he asked in a high squeaky voice.
Sydney stared at him blankly.
‘Say good morning to Aunt Izzy.’
Sydney stared at me blankly.
‘Remember me from last night?’ I asked.
‘Did you have fun?’ Maggie asked.
‘I wouldn’t go that far,’ I replied.
‘I was actually talking to Sydney, Maggie said.
‘Oh well, she’d probably agree. We had an okay time, didn’t we, Sydney?’
‘Why can’t you talk to her like a normal person?’ asked David.
‘I’m the only one talking to her like a normal person. You sound like a eunuch.”