As you know, I'm sure, Collins has completed two other Spillane manuscripts, The Goliath Bone and Dead Street. His name doesn't appear at all on the cover of the latter, and is shown in small letters on the cover of the former. This time, his name is prominently displayed. Maybe that tells us something about the extent of his involvement in each of the books. Maybe not. It doesn't matter, anyway, because there couldn't be anyone better suited to working with Spillane's manuscripts. It's next to impossible (for me, anyway) to tell where Spillane leaves off and Collins begins.
The Big Bang begins with a coincidence. Mike Hammer happens to witness what appears to be a mugging and steps in. People wind up dead. That doesn't surprise you, does it? Anyway, it's a great, violent scene in the Spillane manner. Afterward, Hammer gets interested in the circumstances of the attack and starts to poke around. People start trying to kill him. Naturally this makes him even more interested in finding out what's going on. It has to do with drugs, a very big shipment of them, and the mob and other things. The plot is complex, and Hammer's unraveling of it is satisfactory in the way you'd expect. There's some sex. People die violently.
If you're a fan of the earlier Mike Hammer books (and millions were), you'll like this one. If you're not, this one likely won't convert you. I was a fan. Still am. I'm glad that Collins saved this manuscript and finished it in a way that would make Spillane happy. Check it out.
Update: A don't miss post from Max Allan Collins on the collaborations with Spillane.