Café de Nuit

A player in my campaign wants to design a divination spell that allows him to recieve and understand the thoughts passed back and forth between a wizard and his or her familiar. The reason for this is that another PC always sends her familiar to spy on other PC's and this other PC who wants to design this spell is sort of getting sick of it.

Also, this is a 2nd ed campaign.

Now its not so much that he breaks the link between them or sends in his own thoughts, just hears them. Much like someone picking up a communication on a radio between people with CB's or something.

I am thinking that some material components for this spell might be a piece of hair, nail, eyelash, etc from the wizard and something from the familiar like feather or fur. I am wondering how far the range should be, and what level the spell. Do both the wizard and the familiar have to fail a save, and is there a chance per round or every ten minutes that they can sense something is wrong?

What are some thoughts on this?

Isn't there already rules for an ESP spell? Detect thoughts, was it?

True, I mentioned ESP to the player, but he was more thinking of something for both the caster and familiar. It could be argued that any thoughts the caster send and recieves would be surface thoughts, so I can see your point.

I am under the impression that he wanted something that has a longer range and perhaps duration, so mabye simply a slightly improved ESP.