Complex sentence: Once Tintin returns home, Snowy shows him the scroll and after reading an old message written on it, Tintin puts the scroll in his wallet, but it is stolen by Silk, the next morning.
Split into simpler sentences: Once Tintin returns home, Snowy shows him the scroll. After reading an old message written on it, Tintin puts the scroll in his wallet, but it is stolen by Silk the next morning.