... this short story compilation from the British Library Crime Classics series looks like it would fit the bill.  (Link to Obi's review in the header and here.)

Note: For those looking for a print edition, I've also added the paperback edition to this post.

I don't generally read Kindle books and I already own almost all of these either in e-book form or in paperback, but I got them anyway. Free is nice, and I could see myself rereading them while waiting in line at the grocery store. Also, I used my "purchase" of the Kindle version of Binary Witness to get the audibook for $1.99 on Audible. I've been wanting to listen to it for a while, and since it's an Audible Exclusive, I don't think it's possible to ever find it in Overdrive.

If you don't know about this series, it stars an agoraphobic hacker and the ex-con who manages to convince her to let him clean her house and occasionally make her something to eat.

SF Mysteries/Thrillers are a favorite of mine, and although I own (but haven't yet read) several of these, there are also several here that I either didn't know were thrillers/mysteries or didn't even know about.

Fifty-five years after his death at age 74, the British writer Ernest Bramah continues to bring pleasure to readers and challenge bibliophiles, and he remains an enigma to those who wish to understand him apart from his work. His obituary in the June 29 Times of London is headed "Creator of Kai Lung," and he was best known in his lifetime for the stories and maxims of that itinerent rogue. Set in the lush atmosphere of a China that never was, Kai Lung's adventures are related with humor and irony, his shrewdness and wisdom conveyed in euphemisms, paradoxes and parables.

Read more here. And here. And if you'd like to read his work, here.

I reviewed this a while back and really enjoyed it. I don't know that it's necessarily the best place to start reading the series, since it refers to quite a few things that happened in Book 2, but it might give you an idea if you'd like the author's style. Prior to Claverton putting this up on Smashwords, the only way you could get it was by signing up for her newsletter.

And yes, I know the title on Smashwords says Captcha Thief, but I think the author was just getting her wires crossed and hasn't caught the mistake yet, because Captcha Thief is the third book in the series, due to be released by a small press in a few months. Somehow I doubt she'd be releasing that for free.