I think this was a very important episode for Abby. Despite being the damsel in distress she also shows she doesn't give up hope, stays strong and pugnacious.

The plot needed Caroline to be in the flat, snooping around, but Abby easily could have said to Connor: "My flat, my rules, Caroline can't be in the flat when we're not there." Especially when you realise they have rather secretive jobs.