Disappearing cats

[Pixie129]

My two year old female cat has just returned after being missing for two nights. She is an outdoor cat but we keep her in at night. She has never disappeared for more than about 4hours before.
Much to our relief she had now come back and I have decided to keep her in, at least for this evening. She is not chipped and I want to get her chipped in case she disappears again. However she had only been home about an hour and she is already crying to get out again.
She is uninjured and seems fine - no idea where she has been.
Is she likely to do this again, has she gone by choice or did something untoward happen so she got lost...
Any views? Thinking of getting a tracker.
Our other cat never goes much beyond the garden so no issues with her.

[Madratlady]

My girlcat often goes for a 2 day wander.