There are a lot of freebies this week. First SteamWorld Dig on Origin, then Mirage: Arcane Warfare on Steam and now the first season of Telltale's The Walking Dead is free on Humble Bundle. It can only be claimed for a little more than 40 hours from now on. So hurry!
To get it, login to your Humble Store account. Then add it to your cart and click "Checkout". There you need to click on the blue "Get it for free!". And after a few simple steps it's done!
You must activate the Steam key you claim before 10AM PT on September 23, 2017. After activating the key on your Steam account, it'll be added to your library for ever.