Is a 3.5yr old too young for watching outdoor theatre?

[WeAreGoingOnABearHunt]

I saw that the national trust are doing outdoor theatre shows during summer - do you reckon a 3.5year old could follow the plot and stick with it? She knows the story of the sorcerer's apprentice for example and they are showing that... Tickets are abit pricey so I would really like her to enjoy it. Will also be bringing her little brother (14months) along but as everyone is gonna be sat on the picnic blankets and watching the show, how tolerant are distractions in case he cries or starts crawling around ?

Am I being too ambitious? It will just be me and the 2 kids. Any hints or tips? Thank you!

My little girl went with my mum last year to an outdoor production of the little mermaid, she was 3 years and a few days old. She sat perfectly for the 1.5 hours it was on and although she did speak once or twice, she was no disruption at all and really enjoyed herself.