Netherspace : Netherspace Book 1 : 1

Contact with an alien race, the Gliese, has been made, but communication is impossible. There is trade, but on seemingly inexplicable terms; anti-gravity technology was traded for a bicycle tyre. As we begin to colonize the stars, we're still dependant on the mysterious aliens who we still do not understand.

It falls upon the unlikely team of a conceptual artist, Marc, and assassin, Kara, to embark on a mission that will unearth the mystery of the Gliese.