'How the Dead Speak': Burials and multilayered plots

Prolific Scottish writer Val McDermid sure can spin a crime tale. Forty bodies of young girls are buried on the grounds of a former Catholic orphanage. Did the nuns really abuse them? Then another discovery nearby. Young men. Buried more recently.
This is another in McDermid's series of books featuring psychological profiler Tony Hill (who is in jail now) and detective Carol Jordan, who is no longer on the Regional Major Incident Team but is battling post-traumatic stress disorder.
Other than minor complaints about the opening and the ending, "How the Dead Speak" is a compelling read, with multiple developing plots. It's easy to follow them all and the dialogue keeps one interested with a British touch added: bollocks, gov, bloke et al.
But the reader is left to wonder exactly how Hill and Jordan got into the predicaments they are in, unless you've read the other books in this series. This is the 11th and it ends with one of its big plots unresolved. Must be in the next book.
Those are minor quibbles, though. Overall, McDermid grabs you and won't let you go in this tale which is filled with a large, diverse cast of characters, and intriguing story lines.