How to find a malware app in android

[AC Question]

SOME UNKNOWN APP IS INSTALLED IIN MY DEVICE AUTOMATICALLY WITHOUT MY KNOWLEDGE. ITS NOT DISPLAYED IN THE MENU SCREEN NOR IS IT IN THE APP MANAGER. ONLY A SHORTCUT IS THERE ON THE HOME SCREEN. ITS NOT EVEN THERE IN THE DEVICE ADMINISTRATORS. HOW DO I TRACE WHICH APP IT IS AND UNINSTALL IT. It is displaying some unwanted adware continously and also was downloadinng apps as it wished. It also is displaing some weird sort of lock screen. How do i fing this app