Agreement of past participle

Question

Et ce que j'ai découvert à l'intérieur m'a laissée - Laisser  is conjugated with avoir so why is the past participle agreeing. I guess it has something to do with l'intérieur being feminine but I can't work out why.

Accepted Answer

Bonjour Vikki,
In this sentence, there is a direct object pronoun (m' -> Lydia / a woman -> feminine) placed before the verb 'laisser':
(Lydia speaks)

Son discours m'a laissée sans voix = his speech left me speechless
Cela m'a laissée sans voix = this left me speechless
-> a laissée qui ? = left whom ? -> m' = me (Lydia) -> agreement with the direct object pronoun

See link here (under case of direct object pronouns): special-cases-when-the-past-participle-agrees-in-number-and-gender-when-used-with-avoir-in-le-passe-compose
I hope this is helpful.
Bonne journée !

Answer

The agreement is with the speaker, as she is female:  "It (the thing she found inside) left me (agreement here)speechless."