This is one of the Ace Double volumes, a publishing curiosity extant from the early 1950s to the early 1970s, where two separate books are bound together but published back-to-back and in opposite orientation to one another in what was known as tête-bêche format. Each side had its own cover, so there were two fronts and no backs. This one was published in 1970 and (as I usually say) was a bargain for seventy-five cents. Alton's Unguessable by Jeff Sutton is a pretty good sf adventure, an interstellar exploration novel in the best boldly-go-etc. post Trek tradition. They find some really nasty little telepathic aliens on an out-of-the-way planet. Sutton was a fairly prolific author (he wrote fifteen or twenty novels, several of them YA) from the late 1950s to the early '70s, but isn't much remembered anymore. The story on the flip side is Bulmer's The Ships of Durostorum, one of the novels in his Keys to the Dimensions series. Bulmer always seemed to have cool and catchy titles! It's a very fast-paced adventure in which J.T. Wilkie, a mining engineer, is trapped in a coal mine collapse. He's saved by a beautiful lady with the impressive name Contessa Perdita Francesca Cammachia di Montevarchi, who transports him to a different dimension. It turns out that she's the baddie (which should have been evident because she keeps someone with the rare dimension-shifting ability chained up), and there's a lot of fighting and chasing and dimension-hopping... it's a fun story with plenty of action, and fits in well with the other books in the series. The standard disclaimer is that both novels have a mid-20th century feel and all of the prevailing attitudes of the time. The Bulmer has a kind of kitschy cover by Jack Gaughan and the Sutton has a nifty Kelly Freas cover with birds and a creepy eye. Three stars to both novels.
To the crew of the exploratory vessel Alpha Tauri, Krado 1 was a planetary paradise waiting to be taken. But had nature gone wild? Was evolution non-existent there? No one could understand why, of all the forms of life that might have populated Krado 1, only one species of bird and one species of rodent existed.
The explorers could not have known what lurked behind the thousands of bright, beady eyes… what manifested itself to the telepath Roger Keim as a soundless roar in the corridors of his mind… what was waiting to be released…’
Blurb from the 1970 76096 Ace Doubles paperback edition
This is a very workmanlike variation on the 'alien loose on the ship' story, with echoes of Campbell's 'Who Goes There' and van Vogt's 'Black Destroyer'
An exploratory vessel of The Empire, Alpha Tauri, lands on an uncharted habitable world. Apart from vegetation, the planet seems empty of life apart from one species of bird and one species of rodent. The T-man (telepath), Keim, becomes increasingly nervous as he is hearing a constant roar of mental static. This is because a castaway is already on the planet. Its name is Uli, a virtually immortal being from the edge of the galaxy, and the last survivor of nine who set out to escape an apocalypse in their region of space. Uli - a small egg shaped beast with an eye at one end - has the power to project portions of his being into other creatures, such as the birds and the rodents. His plan is to infect the crew one by one, and to use the ship to take him back to the Empire of the humans where he can begin his conquest of the galaxy. There's a definite van Vogt-ian influence here. The mysterious 'Empire' is mentioned in passing but we are given scant details. Keim is the paradigm of a van Vogt hero, logical and alienated from his peers, but who is eventually proven right. Keim is helped in his battle by Lara, a young crew member who has had to admit her own burgeoning telepathic powers. The major flaw in the structure is that Uli is revealed and explained to the reader immediately in a massive bit of info-dumping which is, one would think, unnecessary. There is an exciting 'battle of wits' denouement in which Keim and Uli both push their powers of cunning to the limit in order to destroy the other.
This is an Ace double, and if you don't know what that means it dates you (as young.) This contains "The Ships of Durostorum" by Kenneth Bulmer, and "Alton's Unguessable" by Jeff Sutton.