Laser Alarm System

Hello Arduino Community!
New to electronics but thanks to arduino I am an addict.

I am creating a laser alarm system for my Escape Room. I am using this build as a basis : http://www.instructables.com/id/Laser-Tripwire-Alarm/

However I want my system to be more complex. I want my alarm system to be connected to an arduino and if someone breaks a beam a signal is sent to the 'clock' arduino that then takes time of the clock. I would to have the alarm system disarmed via a code combination being entered correctly into the arduino.

My questions are:
What shields do I need if any in order to accomplish this?
Could I make several different alarm systems that could send a signal back to the original clock? Bluetooth? Wifi? What's easiest and cheapest!

A laser beam with visible light is, well, visible (dust in the air, scattering at diode and reflector, especially in the dark) and a laser beam with invisible light is a laser class that you cannot safely use for such a problem.

I if you are fine with jamable RF, you can use an ESP8266 (e.g. Wemos D1 Mini) instead of an Arduno AVR.
You don't need shields, shields are for playing.