Complex sentence: Peter discovers that Sharon and Phil are doubting Jake's guilt, so asks Lauren to visit Jake in prison, whilst trying to find the taxi driver who supposedly took Jake and Lucy back to Walford on the night of her death.
Split into simpler sentences: Peter discovers that Sharon and Phil are doubting Jake's guilt, so asks Lauren to visit Jake in prison. He tries to find the taxi driver who brought Jake and Lucy to Walford on the night of her death.