What does “Hold one’s back” mean?

The phrase in the book is:

So they think you're dead, Andrews, and they have now played their last card. So we must hold ours back. You're going to remain dead—for a little while longer.

They're using an analogy to a card game such as poker. They have put their last card down, or made their intentions clear.

But they're going to keep their last card a little longer, and keep their secret from the others: that Andrews is not really dead.

Couldn't that just be a printing mistake, remove the word our and it makes much more sense.

So they (assassins group) think you’re dead, Andrews, and they have now played their last card. So we must hold back, you’re going to remain dead – for a little while longer

especially in the context of the rest of the sentence.