Emsisoft Mobile Security is a simple but effective security solution for Android devices.
The app is lightweight and easy to use, but still manages to cram in plenty of essential features and functionality.
A fast malware scanner checks your apps and stored files for threats; real-time protection detects and blocks malicious apps before they can be installed; web protection prevents you accessing dangerous websites.
A Privacy Audit scans your installed apps, highlighting any which require special permissions (they send or receive data over the internet, can access your personal details, or can cost you money by making calls or sending text messages).
And an Anti-Theft module is able to remotely lock or wipe your device if it's stolen or lost, as well as remotely set the screen unlock password and assorted password rules.