Almost everyone agrees that lying is wrong, and almost everyone does it all the time. Lying is an elegant little book about that paradox.
For obvious reasons, Sam Harris doesn't spend much ink on malicious lies; they're not ethically controversial. His argument, in a nutshell, is that even "white" lies are usually harmful. They're gateway lies that tempt us to other lies. They can be exposed, which destroys trust. They obfuscate information, even when that information can be enlightening. They're often self-serving.
I'm not 100% sold on the conclusion, although as a practicing curmudgeon I consciously attempt to be truthful even when it's not polite. Even so, there are matters whereof I have no particular desire to know the truth. Harris would probably say that in those matters, it's my responsibility not to ask--and I don't! Alas, there are those out there who ask such questions anyway. I won't fib to spare my feelings, but I might do so in order to ... let's say "elide" ... information that the asker doesn't actually want. Harris acknowledges this as a gray area, but his suggested approaches sound mealy-mouthed.
So I don't really live up to Sam Harris's ethical standards. It's a neat book, though. There are lot of challenging ideas, and Harris does a really good job in facing the genuine issues that honesty brings up. I'll look for more of his work.