There is, of course, the very famous book by Barendregt,
- The Lambda Calculus, Its Syntax and Semantics (Studies in Logic and the Foundations of Mathematics, Volume 103). Revised Edition, North-Holland, 1985. (link to vendor)
which doesn't require much background except for the usual mathematical maturity. This is mostly about the untyped lambda calculus. He also has some introductory notes here.