take up where (one) left off
To resume or start (something) again from the last point where one had previously stopped. If it's OK with you, I'd like to go out on a date and try to take up where we left off. The author is taking up where his father left off and finishing the trilogy.
take up where one left off
to start up again in the very place that one has stopped. I had to leave the room for a minute, but when I got back, I took up where I left off. It's time to stop for lunch. After lunch, we will take up where we left off.