“One man is a significant entity. A partnership halves that value. Three or more men, working together, diminish themselves to zero. Team effort is the stagnation of the race.”

As great a booster of John D. MacDonald as I may be, there are entries in his oeuvre that disappoint me. On the Run is one of those, but only because of how it ends – and I think I can guess why it turned out that way.

The titular man on the run in the story, Sid Shanley, is a used car salesman in Houston, living and working under an assumed name. He’s on the run because two years ago he discovered another man in bed with his wife and beat him brutally, leaving him permanently disfigured. The man turned out to be mobster, one inclined to hold grudges over far lesser insults. So Sid took to the road. It was easier to disappear back then than it is now, especially when you’re an orphan. Sid has a brother somewhere, but they’re not in touch.

But Sid isn’t as alone as he thinks. He doesn’t know he has a grandfather, a rich old man living in the town of Bolton out east. The old man is remorseful about the way he treated Sid’s mother, and he wants to see his two grandsons before he dies and leaves them his fortune. He hired a very smart, resourceful investigator to locate Sid, and it was done. He understands that Sid’s going to be hard to approach, so he sends his personal nurse, the lovely Paula Lettinger, as his emissary, carrying a memento he’s sure Sid will recognize.

After a difficult (and pretty weird) first encounter, Sid decides he can trust Paula, and they set off on a cross-country road trip back to Bolton. On the way they’ll discover that they’re made for each other. But as for the future – Sid can’t see how that could ever work out.

There’s a lot of sex in this book – not explicit, but as the focus of Sid’s and Paula’s relationship. Very sophisticated for the time, it all seems a little naïve today. And overdone.

Otherwise, the story goes along great until the very end, when the author clotheslines the reader, bringing the story to what was – for me – a most unsatisfactory conclusion.

But I suspect I can guess what happened to the story. On the Run was published in 1963, the same year the first book in MacDonald’s legendary Travis McGee series appeared. I’m guessing that McGee wasn’t the only series character MacDonald proposed to Fawcett Publications when they asked him to come up with one. I’m guessing that On the Run might have been the first installment in an intriguing series about Sid Shanley pursuing a vendetta against the mob. That would have justified the weird ending we face here.

But that series, if it was ever contemplated, never happened. So we’re left with a decent story that ends with a thud. I can’t really recommend it.