Despite being informed numerous times by Graham Baverstock and his next of kin that Graham had taken an overdose of asprin on Friday night/Saturday morning the Doctor at Scarborough Hospital did a test for paracetamol which of course was clear.
24 hours later Graham goes back to hospital and is correctly tested. The test reveals he has 480 mills per litre in his system. 500 mills is a lethal dose.
What was in his system 24 hours earlier?