Children/YA - Science fiction book about time traveling brother and sister

[Devon]

The only details I am able to recall are that the book is about a brother and sister who use some manner of handheld device to travel back to certain historical time periods. They end up in WW1 era Germany at one point, I think, and they also get chased down by an angry mob at another point. Those are all the details I have. Unfortunately, I can't even recall the names of characters. Any help would be appreciated.

[Lobstergirl, au gratin]

When did you read it?

[Devon]

A bit hard to say for sure. It was definitely sometime in 2017 though. Most likely towards the latter half of the year. That information probably doesn't help too much though.

[Kate]

The Gideon Trilogy?

[Lobstergirl, au gratin]

Devon, are you still looking or did you find this?