Permed to Deadly Perfection (Spring Harbor #7)

When a woman comes in and gets a perm and does not leave a tip, Summer wonders if she is a cheap-skate or something else is happening. When the woman and her husband are found dead in their home from was appears to be carbon monoxide poisoning, Summer just has to get involved.
By the time this one is unraveled, you will wonder how the next book will top this one.