Hanno is a Hitman
He really needs a job.
Hanno lives alone in a studio. He reads newspapers and learns new languages. He takes his daughter for ice cream.
When his agent finds him a contract, the contract is a photo and a plane ticket. He takes the contract without knowing the catch - they want him to use a toxin he is not familiar with.
When the job goes wrong, he's the one who suffers the after-effects of the toxin. And now he can't remember how he got into this mess, but he knows he must get back to his daughter.