Gray Lensman by E. E. "Doc" Smith (1951) starts us up right after the action of Galactic Patrol. Our hero, Kim Kinnison, is once again using all his resources, strength and smarts to try and infiltrate the drug- dealing, power- hoarding, Civilization- hating entity known as Boskone. In doing this, he will have to stretch his power with the Lens beyond that of any other lensman, and although he has a lot of help from his friends, most of the work can only be done by him alone.
Well, him and the brief help of the "trimly attractive blonde" librarian at the Library of Science. The library interaction happens around page 99 on my copy -- worth reading if you are a librarian, but not really worth quoting. The librarian helps Kinnison sort through the great thinkers of the world by running a set of data cards through their computer and selecting for the highest ratings of different criteria. Yay libraries!
There is a lot of great action in this one, and some very fun science (including the creation of a black hole [or a "negasphere"], the towing of a planet from one universe to the next, human regeneration of limbs, and an awesome climax where a key target is destroyed by slamming two uninhabited planets into it from opposite directions). Yay!
And of course, the sexy red-headed nurse, Clarissa MacDougal (the one with the perfect skeleton) isn't forgotten. The sexual tension continues to build through Gray Lensman and by the end it looks like those two crazy kids will finally get together. And breed more perfect skeletons!
[Finally -- isn't the spacesuit on this cover the greatest? If I could make one of these, I might wear it around all the time. I think it would bring me the respect I so greatly deserve.]