Maggie Dove's Detective Agency by Susan Breen

After solving one murder, Maggie has decided to open a detective business.  She's not getting any cases but she's hopeful.  Then when a case is offered, she turns it down.  Her business partner gets very angry with her and tells her to apologize and take the case.  She does, but she'll be sorry.

Alibi and Net Galley let me read this book for review (thank you).  It's being published today, so you can grab a copy now.

Racine asks her to get her long lost sister, Domino, to go home.  She's come to visit with her husband, a maid that sleeps with both of them, and a desire to get some of the money their father left them.  Mom is still alive and she says no.  Domino tells Maggie sometimes people change their minds.  Her sister thinks she's evil.  Maggie isn't sure but she knows she's weird.  She's a witch but she's pursuing black magic.

When she goes to a planned Halloween event, Domino goes to the top of the tower and then falls.  Or was she pushed?  Trying to find anything out around there is impossible.  And the police chief decides it was suicide and quits investigating.  Maggie doesn't.  Not even when her client cancels the contract.

This was a bit of an odd mystery with the witches thrown in.  The people she wanted to talk to didn't want to talk to her.  She keeps working on it, though.  Even when she's not being paid for it.  

She does find the killer but she almost dies in the process.  Domino was not the one that was evil...