HitmanPro is a commercial antivirus tool with some handy free features, which could make a useful addition to your existing antivirus package.
There's no need to install anything; just launch the program, click Next > Next and it will begin to scan your PC. This process only takes a few minutes, after which any suspicious files are uploaded to the HitmanPro servers, and analysed by multiple antivirus tools (Bitdefender, Emsisoft, G Data, IKARUS), before a final report is produced.
All this happens for free (for home users), too, but if you want to remove something then you can only do so within the program's trial period.
While this may not sound too enticing, HitmanPro does have another very important feature in the new KickStart. This allows you to prepare a USB flash drive with its own recovery tool. And if your system is ever infected by ransomware or something similar (malware which is demanding payment to "unlock" your computer), you can boot from the USB drive instead. This boots your own system - not another operating system - in a way which should bypass the ransomware, then helps you to remove it with the minimum of hassle (and without having to pay).
A useful tool which could spot malware your regular antivirus package has missed