In crime novels, and in real life, there is always a point where accomplices, those that know the details decide enough is enough... they can see the outcome , with it's consequent criminal charges, public disgrace, etc all looming up, with dreaded inevitability and things begin to crack and split, even the strongest of bonds...
It has never sat straight with me, that only Chris knows it all. It defies reason that Paul knows nothing. not with the lifelong unbreakable bond between them. Paul may even be the guiding hand in it all.. it's not improbable.....
but in the end, and it is approaching that tipping point, someone decides to blab and blab and blab and blab!!.. my money is on Marilyn!...