This is book 31 of the "Spenser" series.

This note contains spoilers for the book.

I seem to be a bit behind on Spenser novels. This one was pretty good, too.

A high-profile divorce tied to a high-tech financial company gets complicated, and people start dying. Spenser sorts it out eventually, with some help from Hawk.

There are nice bits, like when he exchanges cards with one of the other PIs he finds tailing people. There appears to be a bit where he accepts "Spenser" as his last name, which I don't remember before, but he may have been just not making an issue of it.