Writers of a series of mysteries have a terrific challenge. Maintaining plotting and character, developing depth without disappointing the faithful readership is a burden. I've been disappointed before: even the sainted Agatha Christie repeated her plots, Elizabeth George deteriorated as the Lynley series progressed, Donna Leon lost her way with her charming detective Brunetti (the books became polemics), and even the Camilleri's latest Montalbano offering isn't quite up to his usual excellence. My personal 'never fail' serial writers are Reginald Hill and Magadalen Nabb. Both authors have died (Mr. Hill very recently), so I am confident in saying, minor nitpicking aside, they maintained their skill and mastery throughout.
I really have my fingers crossed for Colin Cotterill. I'm 4 books down so far(have to go back for the two I missed ). He has been taking huge chances - and pulling it off!
He has invented a terrific protagonist in Dr. Siri, but it is the rest of the recurring characters where he has done something I don't recall seeing before--he makes them so human that you wonder for a while if you still like them at all--and then redeems the relationship without forgiving or 'curing' the faults. Amazing! (I am working hard to avoid spoilers here.) Imagine that! He takes a character you quite like and makes them less admirable, and convinces you to mostly, if not quite fully, forgive them. His characters don't just have idiosyncrasies, they have character flaws. And this in a series whose tone is light.
Oh yes, the tone/theme thing. Cotterill lives in Southeast Asia and clearly part of his purpose is to reveal to ignorant westerners (me)something of the history and culture of his adopted region--but there is no exposition here, no preaching. His hero is a communist, and the tension and disappointment between his ideals and the results of the communist revolution is obvious. But Dr. Siri doesn't abandon ideals -- he just laughs at the foibles of human nature that prevent human ideals from becoming realized. Aimed at a western audience, we find ourselves rooting for a commie whose wry acceptance of paradox is comforting and reassuring. Amazing.
And just for fun, he tosses in a lumpy transvestite fortune teller, a fatalistic sense that magic exists, and some quick, hilarious side characters to populate this full world.