Storing books while travelling via Beijing

I will be visiting both North and South Korea travelling through Beijing. It seems best not to take the South Korean guides books into North Korea where I will be first - is there a place they could be left for a week? On the way out, we will only be stopping over in the airport, not any hotel where I could leave them. It would also be nice to leave a tablet computer in Beijing if it is safe, locked and not terribly expensive for a week. Are such options are available. Lockers? or some other arrangement? How does one do this?
Thanks!