Let me be clear: This is not a circus. This is a murder investigation.
-- Detective-Sergeant Adrian Quinlan (Chapter 1 paragraph 43)

Importance: The quote from the detective is the first sign to the readers that someone has been killed, and nearly the rest of the book is about discovering who was killed and why.

She didn’t tell Madeline that she’d been taking six-month leases in different rental apartments across Sydney ever since Ziggy was a baby, trying to find a life that worked. She didn’t tell her that, maybe the whole time, she’d been circling closer and closer to Pirriwee Beach.
-- Jane (Chapter 4 paragraph 31)

Importance: This is the first time that Jane hints there was something in her past that was causing her to constantly travel, each time pushing her closer to Pirriwee.

All around her was color: rich, vibrant color. She was the only colorless thing in this whole house
-- Jane (Chapter 15 paragraph 112)

Importance: This is one of the first signs...