There really don't seem to be an awful lot of good, evangelical resources on the doctrine of sin, and yet it is such a foundational doctrine. But if you do want some more detailed, yet very accessible and clear teaching on the doctrine of sin, I recommend Mike Reeves' talks on Sin and Evil (first two parts, last part). (In fact, I'm sure my 20 minute, boiled down session on sin bears more than a passing resemblance to parts of Reeves' presentation in the main points - and I gratefully acknowledge the influence of his teaching.)
All the Basic Theology talks so far are on the Audio page (see the Tab at the top). Tonight we'll be looking at Jesus Our Substitute.