When an investigator becomes delayed, he tips his Investigator token on its side to remember that he is Delayed.
A Delayed investigator cannot perform any action. This is true even if he would be granted an additional action out of his turn, for example from Charlie Kane's ability.[1]
Instead of performing actions during the Action Phase, a delayed investigator rights his Investigator token and is no longer delayed. This is true even if the investigator cannot perform actions, such as while he has a Detained or Lost in Time and Space Condition.[2]
If an investigator would become Delayed on his turn during the Action Phase, he immediately ends his action and loses all remaining actions instead of becoming Delayed.[3]
Becoming Delayed while already Delayed has no effect. An investigator cannot choose to become Delayed to pay for an effect if he is already Delayed.[3]
Being delayed only prevents an investigator from performing actions. Any other effects are allowed, even if they mimic the effects of actions. Being given a Charter Flight would allow the Delayed investigator to move as instructed.[4]