Don't mess with the Bird Sisters! — James Patterson; Candice Fox

Patterson's greatest crime-solving team since the Women's Murder Club is the Bird Sisters. 

Rhonda and Barbara “Baby” Bird share a late father and not much else -- except the 2 Sisters Detective Agency they founded in Los Angeles. 
 
They take the case of Troy Hansen, a loner whose popular wife has gone missing. Hansen brings them a box of clues pointing to a serial killer responsible for a dozen LAPD cold cases. 
 
Hansen is charged with murder.  Rhonda and Baby are accused of being PIs who can't tell a client from a killer. 
 
But the one other thing these sisters have in common is their willingness to fight: fight the system, fight for the underdog, and fight for the truth … if they can stop fighting each other long enough to work together.