A computer system detects that a mobile device of a user is in a location that exceeds a threshold distance from a second device of the user. Based on at least the detecting, the computer system switches the mobile device to stealth mode, wherein switching the mobile device to stealth mode includes determining an image that visually matches a surface directly below the mobile device, and displaying the image on at least one display of the mobile device. The computer system determines that the second device of the user is located within the threshold distance of the mobile device. Based on the determining, the computer system initiates one or more actions to alert the user as to the location of the mobile device.